The Code Project Latest postings for Clever Code

file converstion

anikbutt22 — Tue, 07 Feb 2012 11:11:00 GMT

hey plz can anybody tell me how can i convert files(doc,pdf etc) to UDF(universal disk format) using .net libraries... if not. then tell me is there any other software third party?

Linq2Horror

Robert Rohde — Wed, 25 Jan 2012 08:01:00 GMT

Hi all,

I think the following could also qualify as a coding horror but I intentionally wrote it this way (one giant linq statement) because of a discussion with a collegue:

Directory.EnumerateFiles(args[0], "*.cs", SearchOption.AllDirectories).AsParallel().Select(f => new { File = f, Bytes = File.ReadAllBytes(f) }).Select(f => new { File = f.File, Bytes = f.Bytes, Encoding = f.Bytes.Take(3).SequenceEqual(new byte[] { 239, 187, 191 }) ? Encoding.UTF8 : Encoding.Default }).ForAll(f => File.WriteAllText(f.File, f.Encoding.GetString(f.Bytes).Split(new string[] { Environment.NewLine }, StringSplitOptions.None).Select(l => new { Line = l, Index = l.Select((c, i) => new { Char = c, Index = i }).FirstOrDefault(c => c.Char != ' ' && c.Char != '\t') }).Select(l => l.Index == null ? l.Line : l.Line.Select((c, i) => (i < l.Index.Index && c == '\t') ? "    " : c.ToString()).Aggregate((s1, s2) => s1 + s2)).Aggregate((s1, s2) => s1 + Environment.NewLine + s2), f.Encoding));

Here another version where I tried to get a proper formatting:

static void Main(string[] args)
{
    Directory.EnumerateFiles(args[0], "*.cs", SearchOption.AllDirectories).
        AsParallel().
        Select(f => new {
            File = f,
            Bytes = File.ReadAllBytes(f)
        }).
        Select(f => new {
            File = f.File,
            Bytes = f.Bytes,
            Encoding = f.Bytes.Take(3).SequenceEqual(new byte[] { 239, 187, 191 })
                ? Encoding.UTF8 : Encoding.Default
        }).
        ForAll(f => File.WriteAllText(f.File,
            f.Encoding.GetString(f.Bytes).Split(
                new string[] { Environment.NewLine }, StringSplitOptions.None).
            Select(l => new { Line = l, Index = l.
                Select((c, i) => new { Char = c, Index = i }).
                FirstOrDefault(c => c.Char != ' ' && c.Char != '\t') }).
            Select(l => l.Index == null ? l.Line : l.Line.
                Select((c, i) => (i < l.Index.Index && c == '\t')
                    ? "    " : c.ToString()).Aggregate((s1, s2) => s1 + s2)).
                Aggregate((s1, s2) => s1 + Environment.NewLine + s2), f.Encoding));
}

So what does this do?
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
args[0] should be a directory where C#-Files are located (*.cs). It opens all files, does a bit of Encoding-analysis (this might not work in every case but its fine for me), replaces Tabs at the beginning of each line with whitespaces (4 for each tab), removes alle whitespaces and tabs in otherwise totally empty lines and writes the file back with the proper encoding.

Interestingly this runs faster than I would have expected. For a codebase with about 8800 files it runs just a few seconds. I would even think (haven't measured it) that searching, reading and writing the files is more time consuming than the rest of the linq in between.

Robert

Vim (linux) regex to create links

Kevin Schaefer — Fri, 20 Jan 2012 23:50:00 GMT

I've been working on about a dozen web pages that I updated. These pages have tables of courses that students can take, and the the page they link to changed. So, after a quick search, I used this regex in Vim (one of the best text editors):

:%s/<td>\(\w\+\)\s\(\d\+\)<\/td>/<td><a href="courses.php?course=\1%20\2">\1 \2<\/a><\/td>/i

Single Update Query for.....

guptasanjay56 — Wed, 18 Jan 2012 14:36:00 GMT

    create table trns.a(id int,name varchar(20))
insert into TRNS.a values(1,'A')
insert into TRNS.a values(2,'B')
insert into TRNS.a values(3,'C')
insert into TRNS.a values(4,'D')
insert into TRNS.a values(5,'E')
insert into TRNS.a values(6,'F')
 
select *from a
if you run select Query, you will get
id  name
-------------------
1   A
2   B
3   C
4   D
.   .
.   .
 
Q. I need to Update the above table in single update statement to get result like
select *from a
 
id  name
-------------------
1   B
2   A
3   D
4   C
.   .
.   .
 
Note: I know the solution, So I have put this question under "Clever Code".

The mystery function

Pascal Ganaye — Mon, 09 Jan 2012 08:49:00 GMT

This is a little game.

Someone in CodeProject wrote this:
I'll let you guess what this does and how it should be named:

static int f(int v)
{
    unchecked
    {
 
        v--;
        v |= v >> 1;
        v |= v >> 2;
        v |= v >> 4;
        v |= v >> 8;
        v |= v >> 16;
        v++;
    }
    return v;
}

For the record when I posted this I promise did not realize that previous post was speaking about the exact same thing.
How extraordinary is this?

Cool bitwise trick page

Jacek Gajek — Wed, 28 Dec 2011 11:46:00 GMT

Bit hacks[^]
For example: Round up to the next highest power of 2:

unsigned int v; // compute the next highest power of 2 of 32-bit v

v--;
v |= v >> 1;
v |= v >> 2;
v |= v >> 4;
v |= v >> 8;
v |= v >> 16;
v++;

This makes my previous code soooo lame (Math.Pow(2,Math.Log(v,2)+1)) or sth like this).

Greetings - Jacek

Translating a jagged array

Jacek Gajek — Sun, 04 Dec 2011 14:33:00 GMT

The code below translates a jagged array. For a jagged array A, the result is a n*m jagged array, where the outer size is n=max(A[i].Length) and the inner size of each subarray is m=A.GetLength(0).
Remark: Holes after null or incomplete subarrays will be filled with default(T).
Usage:

MyType[][] array = ...;
MyType[][] translated = array.Translate();

For examle:
1.

array = new int[5][] { 
    new int[]  { 5, 6, 7    },
    new int [] { 1, 2, 3, 4 },
    new int [] {            },
    new int [] { 0, 1       },
    null,
};
expected = new int[4][] { 
    new int[] { 5, 1, 0, 0, 0 },
    new int[] { 6, 2, 0, 1, 0 },
    new int[] { 7, 3, 0, 0, 0 },
    new int[] { 0, 4, 0, 0, 0 },
};

array = new int[2][] { 
    null,
    null,
};
expected = new int[1][] { 
    new int[] { 0, 0 },
};

For nullable types, there would be null instead of 0.

public static class JaggedArrayExtensions
{ 
    /// <summary>
    /// Translates a given jagged array. Holes after null or incomplete subarrays will be fileld with default(T).
    /// </summary>
    /// <typeparam name="T">Type of elements in the array</typeparam>
    /// <param name="array">The array to translate</param>
    /// <returns>A n*m jagged array, where the outer size is n=max(A[i].Length) and 
    /// the inner size of each subarray is m=A.GetLength(0).</returns>
    public static T[][] Translate<T>(this T[][] array)
    {
        if (array == null)
            throw new ArgumentNullException();
        if (array.Length == 0)
            return new T[0][];
        int columnCount = array.Max(sub => sub == null ? 1 : sub.Length);
        int rowCount = array.Length;
        T[][] res = new T[columnCount][];
        for (int i = 0; i < columnCount; i++)
        {
            res[i] = new T[rowCount];
            for (int j = 0; j < rowCount; j++)
            {
                if (array[j] == null || i >= array[j].Length)
                    res[i][j] = default(T);
                else
                    res[i][j] = array[j][i];
            }
        }
        return res;
    }
}

Greetings - Jacek

For peer review: InputBox.

Timothy CIAN — Tue, 22 Nov 2011 20:06:00 GMT

Purpose: A simple data entry dialog, functionally similar to MessageBox. Feedback is welcomed.

// Sample Utilization:

//Example 1
string s = string.Empty;
if (InputBox.ShowDialog("Type your name:", ref s) == DialogResult.Cancel) return;
 
//Example 2
int x = ((int?)InputBox.Create("Multiply by 2:", "1") ?? 0) * 2;

InputBox Class

/// <summary>
/// Input dialog box used for simple user data entry.
/// </summary>
public static class InputBox
{
    /// <summary>
    /// Standard DialogResult method used for simple user input.
    /// </summary>
    /// <param name="caption">Title for the Input form.</param>
    /// <param name="defaultValue">Default to be displayed in the textbox.</param>
    /// <returns>DialogResult, and updates the value of reference parameter 
    /// defaultValue if the result is DialogResult.OK.</returns>
    public static DialogResult ShowDialog(string caption, ref string defaultValue)
    {
        InputForm inForm = new InputForm(caption, defaultValue);
 
        if (inForm.ShowDialog() == DialogResult.OK)
        {
            defaultValue = inForm.StringValue;
            return DialogResult.OK;
        }
        return DialogResult.Cancel;
    }
 
    /// <summary>
    /// Direct InputBox method, used for immediate typecasting.
    /// Shows the dialog as part of its creation.
    /// </summary>
    /// <param name="caption">Title for the Input form.</param>
    /// <param name="defaultValue">Default to be displayed in the textbox.</param>
    /// <returns>InputForm ready to be typecast to the appropriate value type.</returns>
    public static InputForm Create(string caption, string defaultValue)
    {
        InputForm inForm = new InputForm(caption, defaultValue);
        if (inForm.ShowDialog() == DialogResult.Cancel) inForm.StringValue = string.Empty;
        return inForm;
    }
}

InputForm (used by InputBox)

/// <summary>
/// Display class for InputBox.  Should not be used directly, use InputBox instead.
/// </summary>
public partial class InputForm : Form
{
    #region Constructors
 
    /// <summary>
    /// Default constructor.
    /// </summary>
    public InputForm()
    {
        InitializeComponent();
    }
 
    /// <summary>
    /// Parameterized constructor.
    /// </summary>
    /// <param name="caption">Title for the Input form.</param>
    /// <param name="defaultValue">Default to be displayed in the textbox.</param>
    public InputForm(string caption, string defaultValue) : this()
    {
        this.Text = caption;
        txtValue.Text = defaultValue;
    }
 
    #endregion Constructors
 
    #region Public Properties
 
    /// <summary>
    /// Accessor for the textbox value.
    /// </summary>
    public string StringValue
    {
        get { return txtValue.Text; }
        set { txtValue.Text = value; }
    }
 
    #endregion Public Properties
 
    #region Typecasting Operators
 
    /// <summary>
    /// Typecasting operator.
    /// </summary>
    /// <param name="inForm">Completed InputForm with user entry.</param>
    /// <returns>Nullable value: double.</returns>
    public static explicit operator double?(InputForm inForm)
    {
        if (inForm.StringValue == string.Empty) return null;
        try { return double.Parse(inForm.StringValue); }
        catch { return null; }
    }
 
    /// <summary>
    /// Typecasting operator.
    /// </summary>
    /// <param name="inForm">Completed InputForm with user entry.</param>
    /// <returns>Nullable value: int.</returns>
    public static explicit operator int?(InputForm inForm)
    {
        if (inForm.StringValue == string.Empty) return null;
        try { return Int32.Parse(inForm.StringValue); }
        catch { return null; }
    }
 
    /// <summary>
    /// Typecasting operator.
    /// </summary>
    /// <param name="inForm">Completed InputForm with user entry.</param>
    /// <returns>Nullable value: long.</returns>
    public static explicit operator long?(InputForm inForm)
    {
        if (inForm.StringValue == string.Empty) return null;
        try { return Int64.Parse(inForm.StringValue); }
        catch { return null; }
    }
 
    /// <summary>
    /// Typecasting operator.
    /// </summary>
    /// <param name="inForm">Completed InputForm with user entry.</param>
    /// <returns>String value.</returns>
    public static explicit operator string(InputForm inForm)
    {
        return inForm.StringValue;
    }
 
    #endregion Typecasting Operators
}

ProjectEuler problem 24 solution - in PDP/8 assembly language

MrChug — Fri, 04 Nov 2011 17:09:00 GMT

I solved this in PDP/8 assembly language PAL/8. It's a brute force loop unrolled for the /8. The answer is in octal so don't panic.

.PAL E24,E24<E24/G
 
HALT instruction, PC: 00442 (JMP I 443)
sim> E 20:31    / examine the answer
20:     0002
21:     0007
22:     0010
23:     0003
24:     0011
25:     0001
26:     0005
27:     0004
30:     0006
31:     0000
sim> G 7600     /  back to the monitor
.

Recent work for $(DAYJOB) has triggered memories of PDP/8, PAL/8, OS/8, FOTP, PIP, ODT, and the whole suite of stuff from the dark ages [1]. Here's my source code listing:

.TYPE E24.LS
 
/ PROJECTEULER.NET PROBLEM 24             PAL8-V12B 02-NOV-77 PAGE 1
 
             / PROJECTEULER.NET PROBLEM 24
             /
             / A PERMUTATION IS AN ORDERED ARRANGEMENT OF OBJECTS.
             / FOR EXAMPLE, 3124 IS ONE POSSIBLE PERMUTATION OF
             / THE DIGITS 1, 2, 3 AND 4. IF ALL OF THE PERMUTATIONS
             / ARE LISTED NUMERICALLY OR ALPHABETICALLY,
             / WE CALL IT LEXICOGRAPHIC ORDER.
             / THE LEXICOGRAPHIC PERMUTATIONS OF 0, 1 AND 2 ARE:
             /
             /     012   021   102   120   201   210
             /
             / WHAT IS THE MILLIONTH LEXICOGRAPHIC PERMUTATION
             / OF THE DIGITS 0, 1, 2, 3, 4, 5, 6, 7, 8 AND 9?
             /
             / PAL/8 DIGITAL EQUIPMENT CORPORATION (DEC) PDP/8
             / ASSEMBLY LANGUAGE SOLUTION BY CHUCK ROLKE, 2-NOV-2011
             /
       0010          *10
00010  0000  CHKPTR, 0
 
       0020          *20
                                             / SOLUTION IS CONSTRUCTED HERE
00020  0000  D0,     0
00021  0000  D1,     0
00022  0000  D2,     0
00023  0000  D3,     0
00024  0000  D4,     0
00025  0000  D5,     0
00026  0000  D6,     0
00027  0000  D7,     0
00030  0000  D8,     0
00031  0000  D9,     0
                                             / COUNTERS
00032  0000  C0,     0
00033  0000  C1,     0
00034  0000  C2,     0
00035  0000  C3,     0
00036  0000  C4,     0
00037  0000  C5,     0
00040  0000  C6,     0
00041  0000  C7,     0
00042  0000  C8,     0
00043  0000  C9,     0
                                             / SUBR POINTERS
00044  0202  PTR0,   S0
00045  0215  PTR1,   S1
00046  0233  PTR2,   S2
00047  0251  PTR3,   S3
00050  0267  PTR4,   S4
00051  0305  PTR5,   S5
00052  0323  PTR6,   S6
00053  0341  PTR7,   S7
00054  0400  PTR8,   S8
00055  0416  PTR9,   S9
                                             / SEARCH COUNT
 
/ PROJECTEULER.NET PROBLEM 24             PAL8-V12B 02-NOV-77 PAGE 1-1
 
00056  6700  CLO,    6700                    / -1000000  LOW 12 BITS
00057  7413  CHI,    7413                    / -1000000 HIGH 12 BITS
 
00060  0017  PD0M1,  D0-1                    / AUTOINCREMENT PTR TO D0
00061  7766  KM10,   -12                     / MINUS 10.
 
             /
             / CHK - IS A DIGIT USED YET?
             /       RETURN AC==0 YES, DIGIT IN USE
             /              AC!=0  NO, DIGIT IS AVAILABLE TO USE
00062  0000  CHK,    0
00063  7200          CLA                     / AC=0
00064  1462          TAD I   CHK             / GET ADDRESS OF DIGIT TO TEST FO
00065  2062          ISZ     CHK
00066  3110          DCA     CHKTP           / SAVE TEST DIGIT ADDRESS
00067  1510          TAD I   CHKTP           / READ THE DIGIT
00070  7041          CIA                     / NEGATE IT
00071  3110          DCA     CHKTP           / SAVE TEST VALUE
00072  1462          TAD I   CHK             / GET NEGATIVE NUMBER OF DIGITS
00073  2062          ISZ     CHK
00074  3111          DCA     CHKCNT          / SAVE COUNT
00075  1060          TAD     PD0M1           / GET ADDRESS OF FIRST DIGIT
00076  3010          DCA     CHKPTR          / SAVE ADDRESS OF DIGIT TO TEST
00077  7200  CHKL,   CLA                     / AC=0
00100  1410          TAD I   CHKPTR          / READ NEXT DIGIT TO TEST
00101  1110          TAD     CHKTP           / COMPARE TO VALUE TO TEST
00102  7450          SNA                     / SKIP IF VALUE TEST FAILS
00103  5462          JMP I   CHK             / RETURN 0 IF DIGIT IN USE
00104  2111          ISZ     CHKCNT          / COUNT DIGITS TESTED
00105  5077          JMP     CHKL            / JUMP TO TEST NEXT
00106  7240          CLA CMA                 / SET TO NONZERO
00107  5462          JMP I   CHK             / RETURN NZ AS DIGIT IS UNUSED
00110  0000  CHKTP,  0                       / PTR TO AND VAL OF DIGIT TO TEST
00111  0000  CHKCNT, 0                       / NEGATIVE COUNT OF DIGITS TO TES
 
       0200          *200
                                             / MAIN ENTRY POINT
00200  4444  START,  JMS I   PTR0            / CALL SOLUTION ENGINE
00201  7402          HLT                     / UH, OH. NO SOLUTION FOUND.
 
                                             / S0 - SOLVE DIGIT D0
00202  0000  S0,     0
00203  7402          HLT
00204  7200          CLA
00205  3020          DCA     D0
00206  1061          TAD     KM10
00207  3032          DCA     C0
00210  4445  S0L,    JMS I   PTR1
00211  2020          ISZ     D0
00212  2032          ISZ     C0
00213  5210          JMP     S0L
00214  5602          JMP I   S0
 
                                             / S1 - SOLVE DIGIT D1
00215  0000  S1,     0
 
/ PROJECTEULER.NET PROBLEM 24             PAL8-V12B 02-NOV-77 PAGE 1-2
 
00216  7200          CLA
00217  3021          DCA     D1
00220  1061          TAD     KM10
00221  3033          DCA     C1
00222  4062  S1L,    JMS     CHK
00223  0021          D1
00224  7777          -1
00225  7440          SZA
00226  4446          JMS I   PTR2
00227  2021          ISZ     D1
00230  2033          ISZ     C1
00231  5222          JMP     S1L
00232  5615          JMP I   S1
 
                                             / S2 - SOLVE DIGIT D2
00233  0000  S2,     0
00234  7200          CLA
00235  3022          DCA     D2
00236  1061          TAD     KM10
00237  3034          DCA     C2
00240  4062  S2L,    JMS     CHK
00241  0022          D2
00242  7776          -2
00243  7440          SZA
00244  4447          JMS I   PTR3
00245  2022          ISZ     D2
00246  2034          ISZ     C2
00247  5240          JMP     S2L
00250  5633          JMP I   S2
 
                                             / S3 - SOLVE DIGIT D3
00251  0000  S3,     0
00252  7200          CLA
00253  3023          DCA     D3
00254  1061          TAD     KM10
00255  3035          DCA     C3
00256  4062  S3L,    JMS     CHK
00257  0023          D3
00260  7775          -3
00261  7440          SZA
00262  4450          JMS I   PTR4
00263  2023          ISZ     D3
00264  2035          ISZ     C3
00265  5256          JMP     S3L
00266  5651          JMP I   S3
                                             / S4 - SOLVE DIGIT D4
00267  0000  S4,     0
00270  7200          CLA
00271  3024          DCA     D4
00272  1061          TAD     KM10
00273  3036          DCA     C4
00274  4062  S4L,    JMS     CHK
00275  0024          D4
00276  7774          -4
00277  7440          SZA
 
/ PROJECTEULER.NET PROBLEM 24             PAL8-V12B 02-NOV-77 PAGE 1-3
 
00300  4451          JMS I   PTR5
00301  2024          ISZ     D4
00302  2036          ISZ     C4
00303  5274          JMP     S4L
00304  5667          JMP I   S4
 
                                             / S5 - SOLVE DIGIT D5
00305  0000  S5,     0
00306  7200          CLA
00307  3025          DCA     D5
00310  1061          TAD     KM10
00311  3037          DCA     C5
00312  4062  S5L,    JMS     CHK
00313  0025          D5
00314  7773          -5
00315  7440          SZA
00316  4452          JMS I   PTR6
00317  2025          ISZ     D5
00320  2037          ISZ     C5
00321  5312          JMP     S5L
00322  5705          JMP I   S5
 
                                             / S6 - SOLVE DIGIT D6
00323  0000  S6,     0
00324  7200          CLA
00325  3026          DCA     D6
00326  1061          TAD     KM10
00327  3040          DCA     C6
00330  4062  S6L,    JMS     CHK
00331  0026          D6
00332  7772          -6
00333  7440          SZA
00334  4453          JMS I   PTR7
00335  2026          ISZ     D6
00336  2040          ISZ     C6
00337  5330          JMP     S6L
00340  5723          JMP I   S6
 
                                             / S7 - SOLVE DIGIT D7
00341  0000  S7,     0
00342  7200          CLA
00343  3027          DCA     D7
00344  1061          TAD     KM10
00345  3041          DCA     C7
00346  4062  S7L,    JMS     CHK
00347  0027          D7
00350  7771          -7
00351  7440          SZA
00352  4454          JMS I   PTR8
00353  2027          ISZ     D7
00354  2041          ISZ     C7
00355  5346          JMP     S7L
00356  5741          JMP I   S7
 
       0400          *400
 
/ PROJECTEULER.NET PROBLEM 24             PAL8-V12B 02-NOV-77 PAGE 1-4
 
                                             / S8 - SOLVE DIGIT D8
00400  0000  S8,     0
00401  7200          CLA
00402  3030          DCA     D8
00403  1061          TAD     KM10
00404  3042          DCA     C8
00405  4062  S8L,    JMS     CHK
00406  0030          D8
00407  7770          -10
00410  7440          SZA
00411  4455          JMS I   PTR9
00412  2030          ISZ     D8
00413  2042          ISZ     C8
00414  5205          JMP     S8L
00415  5600          JMP I   S8
 
                                             / S9 - SOLVE DIGIT D9
00416  0000  S9,     0
00417  7200          CLA
00420  3031          DCA     D9
00421  1061          TAD     KM10
00422  3043          DCA     C9
00423  4062  S9L,    JMS     CHK
00424  0031          D9
00425  7767          -11
00426  7440          SZA
00427  4234          JMS     TESTD
00430  2031          ISZ     D9
00431  2043          ISZ     C9
00432  5223          JMP     S9L
00433  5616          JMP I   S9
                                             / TESTD - ANOTHER ITER COMPLETE
00434  0000  TESTD,  0
00435  2056          ISZ     CLO
00436  5634          JMP I   TESTD
00437  2057          ISZ     CHI
00440  5634          JMP I   TESTD
                                             / 1,000,000TH FOUND
00441  7402          HLT
 
00442  5643          JMP I   MON
00443  7600  MON,    7600
             $
 
/ PROJECTEULER.NET PROBLEM 24             PAL8-V12B 02-NOV-77 PAGE 2
 
CHI    0057      S7     0341
CHK    0062      S7L    0346
CHKCNT 0111      S8     0400
CHKL   0077      S8L    0405
CHKPTR 0010      S9     0416
CHKTP  0110      S9L    0423
CLO    0056      TESTD  0434
C0     0032
C1     0033
C2     0034
C3     0035
C4     0036
C5     0037
C6     0040
C7     0041
C8     0042
C9     0043
D0     0020
D1     0021
D2     0022
D3     0023
D4     0024
D5     0025
D6     0026
D7     0027
D8     0030
D9     0031
KM10   0061
MON    0443
PD0M1  0060
PTR0   0044
PTR1   0045
PTR2   0046
PTR3   0047
PTR4   0050
PTR5   0051
PTR6   0052
PTR7   0053
PTR8   0054
PTR9   0055
START  0200
S0     0202
S0L    0210
S1     0215
S1L    0222
S2     0233
S2L    0240
S3     0251
S3L    0256
S4     0267
S4L    0274
S5     0305
S5L    0312
S6     0323
S6L    0330
 

 
ERRORS DETECTED: 0
LINKS GENERATED: 0

[1]
* Note the listing year is '77'. OS/8 had too few bits for the year field, way ahead of its time.
* Octal?
* All upper case - we're talking teletypes, my friends.
* I coded one routine with the classic dense comments. The rest - you're on your own.
* There's no self modifying code. I'm a purist. Would Atlant approve?
* My real PDP/8-M died a few years back. Coded on Mr. Bob Supnic's simulator.

Extract from Jigsaw

Pascal Ganaye — Wed, 02 Nov 2011 10:00:00 GMT

This is an extract from the 'Implementing Programming Languages using C# 4.0' article published last week (late oct 2011)

Some of the code really blow my mind.
This code works, but how on earth does it work?
I need to spend spend some time on this.

        public delegate Lambda Lambda(Lambda x);
 
        public static Lambda Id         = x => x;
        public static Lambda Zero       = f => x => x;
        public static Lambda True       = x => y => x;
        public static Lambda False      = x => y => y;
        public static Lambda One        = f => x => f(x);
        public static Lambda Two        = f => x => f(f(x));
        public static Lambda Succ       = n => f => x => f(n(f)(x));
        public static Lambda Three      = Succ(Two);
        public static Lambda Pred       = n => f => x => n(g => h => h(g(f)))(u => x)(Id);
        public static Lambda Plus       = m => n => f => x => m(f)(n(f)(x));
        public static Lambda Sub        = m => n => n (Pred) (m);
        public static Lambda And        = p => q => p(q)(p);
        public static Lambda Or         = p => q => p(p)(q);
        public static Lambda Not        = p => a => b => p(b)(a);
        public static Lambda IfThenElse = p => a => b => p(a)(b);
        public static Lambda IsZero     = n => n(x => False)(True);
        public static Lambda IsLtEqOne  = n => IsZero(Pred(n));
        public static Lambda Pair       = x => y => f => f(x)(y);
        public static Lambda First      = pair => pair(True);
        public static Lambda Second     = pair => pair(False);
        public static Lambda Nil        = x => True;
        public static Lambda Null       = p => p(x => y => False);
        public static Lambda LtEq       = x => y => IsZero(Sub(x)(y));
        public static Lambda Gt         = x => y => LtEq(y)(x);
        public static Lambda Eq         = x => y => And(LtEq(x)(y))(LtEq(y)(x));

Simple Camera Tethering Using WIA

gmillwater — Sat, 29 Oct 2011 19:04:00 GMT

I'm a freelance studio/event photographer. For years I've had to use often expensive and complex software to tether my cameras to my laptop. I needed a fast, lightweight tool to do the job without all the cumbersome tools, so as the saying goes "if you want it done right, do it yourself". Here is a quick and simple framework for tethering Nikon cameras with near instant file transfer and image viewing. This is just a vb.net framework and should be modified to suit your taste. Have fun...

Imports WIA
Imports System.Runtime.InteropServices
Imports System.Environment
Imports System.IO

'Add reference to wiaaut.dll located in \Windows\System32
'Add Panel1 with Dock=Fill and BackgroundImage=Zoom
'Form1.text = Waiting...

Public Class Form1
      Public Const wiaEventItemCreated = "{4C8F4EF5-E14F-11D2-B326-00C04F68CE61}"
      Public Const wiaEventDeviceConnected = "{A28BBADE-64B6-11D2-A231-00C04FA31809}"
      Public Const wiaEventDeviceDisconnected = "{143E4E83-6497-11D2-A231-00C04FA31809}"

      Public WIA_Dialog As New WIA.CommonDialog
      Public WIA_DeviceMgr As New WIA.DeviceManager
      Public WIA_Device As WIA.Device

      Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            WIA_DeviceMgr.RegisterEvent(wiaEventItemCreated, "*")
            WIA_DeviceMgr.RegisterEvent(wiaEventDeviceConnected, "*")
            WIA_DeviceMgr.RegisterEvent(wiaEventDeviceDisconnected, "*")
            AddHandler WIA_DeviceMgr.OnEvent, AddressOf Me.WIA_OnEvent
      End Sub

      Private Sub WIA_OnEvent(ByVal EventID As String, ByVal DeviceID As String, ByVal ItemId As String)
            Dim device As String
            If EventID = wiaEventDeviceConnected Then
                  Try
                        'set param2 to False to automatically select the device
                        'set param2 to True to show device select dialog
                        WIA_Device = WIA_Dialog.ShowSelectDevice(WiaDeviceType.CameraDeviceType, False, True)
                        'display device information
                        device = "Connected To "
                        For Each prop As WIA.Property In WIA_Device.Properties
                              Select Case prop.Name
                                    Case "Manufacturer"
                                          device += prop.Value.ToString & " "
                                    Case "Description"
                                          device += prop.Value.ToString
                              End Select
                        Next
                        Me.Text = device
                  Catch ex As Exception
                        Debug.WriteLine("Error Connecting To Camera")
                  End Try
                  Exit Sub
            End If
            If EventID = wiaEventDeviceDisconnected Then
                  Me.Text = "Waiting..."
                  Me.Panel1.BackgroundImage = Nothing
                  Exit Sub
            End If
            If EventID = wiaEventItemCreated Then
                  Me.Panel1.BackgroundImage = Nothing
                  Dim itm As Item = WIA_Device.GetItem(ItemId)
                  Dim img As ImageFile = itm.Transfer
                  Dim fname As String = "C:\Temp\" & itm.Properties("Item Name").Value & "." & img.FileExtension
                  img.SaveFile(fname)
                  Me.Panel1.BackgroundImage = Image.FromFile(fname)
            End If
      End Sub

End Class

Strange

Pascal Ganaye — Wed, 26 Oct 2011 13:53:00 GMT

Today I just noticed that generally:

power(rand(),2) > rand()*rand()

Practically in excel

rand() * rand() average is 1/4
rand()^2 average is 1/3

It blows my mind.

NTFS, win7 and 20 million files

Michael Pauli — Fri, 09 Sep 2011 10:31:00 GMT

Hi,

I'm about to begin a small project in which I must be able to store and lookup up to 20. mio. files - in the best possible way. Needless to say fast.

For this I have been around -

http://en.wikipedia.org/wiki/NTFS#Limitations
http://www.ntfs.com/ntfs_vs_fat.htm

And now my question: Dealing with a production load in the area around 60.000 files (=pictures) per day each around 300 kb in size, what would be the best ratio of what number of files in what number of directorys to make the search-time best? Obviously I do not put all the files in one directory, but in a number of dir's. So what would be the best economy for such a thing?

Seems to be hard to find information about on the web.

Thanx' in advance,
Kind regards,

Michael Pauli

The quest for fastest strstr-like function in C

Sanmayce — Fri, 02 Sep 2011 17:15:00 GMT

Hi to all C programmers,
my desire is with help of more experienced guys/girls to boost the following function:

// ### Mix(2in1) of Karp-Rabin & Boyer-Moore-Horspool algorithm [
// Caution: For better speed the case 'if (cbPattern==1)' was removed, so Pattern must be longer than 1 char.
char * Railgun_Quadruplet (char * pbTarget,
     char * pbPattern,
     unsigned long cbTarget,
     unsigned long cbPattern)
{
    char * pbTargetMax = pbTarget + cbTarget;
    register unsigned long  ulHashPattern;
    unsigned long ulHashTarget;
    unsigned long count;
    unsigned long countSTATIC;
//  unsigned long countRemainder;

/*
    const unsigned char SINGLET = *(char *)(pbPattern);
    const unsigned long Quadruplet2nd = SINGLET<<8;
    const unsigned long Quadruplet3rd = SINGLET<<16;
    const unsigned long Quadruplet4th = SINGLET<<24;
*/
    unsigned char SINGLET;
    unsigned long Quadruplet2nd;
    unsigned long Quadruplet3rd;
    unsigned long Quadruplet4th;
 
    unsigned long  AdvanceHopperGrass;
 
    long i; //BMH needed
    int a, j, bm_bc[ASIZE]; //BMH needed
    unsigned char ch; //BMH needed
//    unsigned char lastch, firstch; //BMH needed

    if (cbPattern > cbTarget)
        return(NULL);
 
// Doesn't work when cbPattern = 1
// The next IF-fragment works very well with cbPattern>1, OBVIOUSLY IT MUST BE UNROLLED(but crippled with less functionality) SINCE either cbPattern=2 or cbPattern=3!
if ( cbPattern<4) { // This IF makes me unhappy: it slows down from 390KB/clock to 367KB/clock for 'fast' pattern. This fragment(for 2..3 pattern lengths) is needed because I need a function different than strchr but sticking to strstr i.e. lengths above 1 are to be handled.
        pbTarget = pbTarget+cbPattern;
        ulHashPattern = ( (*(char *)(pbPattern))<<8 ) + *(pbPattern+(cbPattern-1));
//        countSTATIC = cbPattern-2;

if ( cbPattern==3) {
    for ( ;; )
    {
        if ( ulHashPattern == ( (*(char *)(pbTarget-3))<<8 ) + *(pbTarget-1) ) {
         if ( *(char *)(pbPattern+1) == *(char *)(pbTarget-2) ) return((pbTarget-3));
        }
        if ( (char)(ulHashPattern>>8) != *(pbTarget-2) ) pbTarget++;
        pbTarget++;
        if (pbTarget > pbTargetMax)
            return(NULL);
    }
} else {
}
    for ( ;; )
    {
        // The line below gives for 'cbPattern'>=1:
        // Karp_Rabin_Kaze_4_OCTETS_hits/Karp_Rabin_Kaze_4_OCTETS_clocks: 4/543
        // Karp_Rabin_Kaze_4_OCTETS performance: 372KB/clock
/*
        if ( (ulHashPattern == ( (*(char *)(pbTarget-cbPattern))<<8 ) + *(pbTarget-1)) && !memcmp(pbPattern, pbTarget-cbPattern, (unsigned int)cbPattern) )
            return((long)(pbTarget-cbPattern));
*/
 
        // The fragment below gives for 'cbPattern'>=2:
        // Karp_Rabin_Kaze_4_OCTETS_hits/Karp_Rabin_Kaze_4_OCTETS_clocks: 4/546
        // Karp_Rabin_Kaze_4_OCTETS performance: 370KB/clock

/*
//For 2 and 3 [
        if ( ulHashPattern == ( (*(char *)(pbTarget-cbPattern))<<8 ) + *(pbTarget-1) ) {
//         count = countSTATIC;
         count = cbPattern-2;
//         while ( count && *(char *)(pbPattern+1+(countSTATIC-count)) == *(char *)(pbTarget-cbPattern+1+(countSTATIC-count)) ) {
         while ( count && *(char *)(pbPattern+1) == *(char *)(pbTarget-2) ) { // Crippling i.e. only 2 and 3 chars are allowed!
               count--;
         }
         if ( count == 0) return((pbTarget-cbPattern));
        }
        if ( (char)(ulHashPattern>>8) != *(pbTarget-cbPattern+1) ) pbTarget++;
//For 2 and 3 ]
*/
 

        if ( ulHashPattern == ( (*(char *)(pbTarget-2))<<8 ) + *(pbTarget-1) )
            return((pbTarget-2));
        if ( (char)(ulHashPattern>>8) != *(pbTarget-1) ) pbTarget++;
 

        // The fragment below gives for 'cbPattern'>=2:
	// Karp_Rabin_Kaze_4_OCTETS_hits/Karp_Rabin_Kaze_4_OCTETS_clocks: 4/554
	// Karp_Rabin_Kaze_4_OCTETS performance: 364KB/clock
/*
        if ( ulHashPattern == ( (*(char *)(pbTarget-cbPattern))<<8 ) + *(pbTarget-1) ) {
         count = countSTATIC>>2;
         countRemainder = countSTATIC % 4;
 
         while ( count && *(unsigned long *)(pbPattern+1+((count-1)<<2)) == *(unsigned long *)(pbTarget-cbPattern+1+((count-1)<<2)) ) {
               count--;
         }
	 //if (count == 0) {  // Disastrous degradation only from this line(317KB/clock when 1+2x4+2+1 bytes pattern: 'skillessness'; 312KB/clock when 1+1x4+2+1 bytes pattern: 'underdog'), otherwise 368KB/clock.
         while ( countRemainder && *(char *)(pbPattern+1+(countSTATIC-countRemainder)) == *(char *)(pbTarget-cbPattern+1+(countSTATIC-countRemainder)) ) {
               countRemainder--;
         }
         //if ( countRemainder == 0) return((long)(pbTarget-cbPattern));
         if ( count+countRemainder == 0) return((long)(pbTarget-cbPattern));
         //}
        }
*/
 
        pbTarget++;
        if (pbTarget > pbTargetMax)
            return(NULL);
    }
} else { //if ( cbPattern<4)
if (cbTarget<961) // This value is arbitrary(don't know how exactly), it ensures(at least must) better performance than 'Boyer_Moore_Horspool'.
{
        pbTarget = pbTarget+cbPattern;
        ulHashPattern = *(unsigned long *)(pbPattern);
//        countSTATIC = cbPattern-1;

    //SINGLET = *(char *)(pbPattern);
    SINGLET = ulHashPattern & 0xFF;
    Quadruplet2nd = SINGLET<<8;
    Quadruplet3rd = SINGLET<<16;
    Quadruplet4th = SINGLET<<24;
 
    for ( ;; )
    {
	AdvanceHopperGrass = 0;
	ulHashTarget = *(unsigned long *)(pbTarget-cbPattern);
 
        if ( ulHashPattern == ulHashTarget ) { // Three unnecessary comparisons here, but 'AdvanceHopperGrass' must be calculated - it has a higher priority.
//         count = countSTATIC;
//         while ( count && *(char *)(pbPattern+1+(countSTATIC-count)) == *(char *)(pbTarget-cbPattern+1+(countSTATIC-count)) ) {
//	       if ( countSTATIC==AdvanceHopperGrass+count && SINGLET != *(char *)(pbTarget-cbPattern+1+(countSTATIC-count)) ) AdvanceHopperGrass++;
//               count--;
//         }
         count = cbPattern-1;
         while ( count && *(char *)(pbPattern+(cbPattern-count)) == *(char *)(pbTarget-count) ) {
	       if ( cbPattern-1==AdvanceHopperGrass+count && SINGLET != *(char *)(pbTarget-count) ) AdvanceHopperGrass++;
               count--;
         }
         if ( count == 0) return((pbTarget-cbPattern));
        } else { // The goal here: to avoid memory accesses by stressing the registers.
    if ( Quadruplet2nd != (ulHashTarget & 0x0000FF00) ) {
         AdvanceHopperGrass++;
         if ( Quadruplet3rd != (ulHashTarget & 0x00FF0000) ) {
              AdvanceHopperGrass++;
              if ( Quadruplet4th != (ulHashTarget & 0xFF000000) ) AdvanceHopperGrass++;
         }
    }
	}
 
	AdvanceHopperGrass++;
 
	pbTarget = pbTarget + AdvanceHopperGrass;
        if (pbTarget > pbTargetMax)
            return(NULL);
    }
} else { //if (cbTarget<961)
        countSTATIC = cbPattern-2;
    /* Preprocessing */
    for (a=0; a < ASIZE; a++) bm_bc[a]=cbPattern;
    for (j=0; j < cbPattern-1; j++) bm_bc[pbPattern[j]]=cbPattern-j-1;
 
    /* Searching */
    //lastch=pbPattern[cbPattern-1];
    //firstch=pbPattern[0];
    i=0;
    while (i <= cbTarget-cbPattern) {
       ch=pbTarget[i+cbPattern-1];
       //if (ch ==lastch)
          //if (memcmp(&pbTarget[i],pbPattern,cbPattern-1) == 0) OUTPUT(i);
          //if (ch == lastch && pbTarget[i] == firstch && memcmp(&pbTarget[i],pbPattern,cbPattern-1) == 0) return(i);  // Kaze: The idea(to prevent execution of slower 'memcmp') is borrowed from Karp-Rabin i.e. to perform a slower check only when the target "looks like".
          if (ch == pbPattern[cbPattern-1] && pbTarget[i] == pbPattern[0])
             {
         count = countSTATIC;
         while ( count && *(char *)(pbPattern+1+(countSTATIC-count)) == *(char *)(&pbTarget[i]+1+(countSTATIC-count)) ) {
               count--;
         }
         if ( count == 0) return(pbTarget+i);
	     }
       i+=bm_bc[ch];
    }
    return(NULL);
} //if (cbTarget<961)
} //if ( cbPattern<4)
}
// ### Mix(2in1) of Karp-Rabin & Boyer-Moore-Horspool algorithm ]

There are tricky and slippery drawbacks as which compiler is used and what options are used. My tests show that this revision (6+) is fastest when Microsoft C v16 (from VisualStudio 2010) is used - it outperforms even the powerful Intel C v12, no joke here.

I would be really glad for any suggestions or ideas how to speed up more the Railgun_Quadruplet.

Oh, I forgot to give the homepage with my latest benchmarks:
http://www.sanmayce.com/Railgun/index.html[^]

My Far Call

MrChug — Fri, 02 Sep 2011 01:42:00 GMT

Windows at Red Hat: my far call.
Seek, climb, ponder, fall, more joy unfound.

Hack stack-tracker before halls template.
Wandering, wondering at core's cold binding lure.

Helpless room full of empty pages make boost.
Style accepted by an eye trained on goals unseen.

Life newly constructed sees not both heaps.
Heaven's world attached keeps a .NET brother.

Unspoken languages, who speaks now? QA checks.
Hear how dear kits near appear. Who speaks now?

Unfolding world's new day sees team progress.

In its gut life passes by: WinSDK.

They will never have seen anything like us them there. - M. Spirito

Queue through all files in a directory (and subdirectories).

Timothy CIAN — Fri, 12 Aug 2011 14:33:00 GMT

Here is an easy way to queue all files in a folder (and subfolders). You only need to initialize it with _folders.Enqueue(SomeRootDirectoryInfo); before using it...

private Queue<DirectoryInfo> _folders = new Queue<DirectoryInfo>();
private Queue<FileInfo> _files = new Queue<FileInfo>();

public FileInfo NextFile
{
    get
    {
        lock (_files)
        {
            if (_files.Count != 0)
                return _files.Dequeue();
            else
            {
                lock (_folders)
                {
                    while (_folders.Count != 0)
                    {
                        DirectoryInfo dir = _folders.Dequeue();
                        foreach (DirectoryInfo d in dir.GetDirectories())
                            _folders.Enqueue(d);
                        foreach (FileInfo f in dir.GetFiles()) 
                            _files.Enqueue(f);
                        if (_files.Count != 0) return _files.Dequeue();
                    }
                }
            }
        }
        return null;  //Default
    }
}

Comment Switching

musefan — Fri, 05 Aug 2011 14:52:00 GMT

I have a static string which I am constantly switch to a known value for debugging. But now I have come up with something that saves me 3 key strokes!!!

consider...

public static string MyString = "";//@"DEBUG VALUE";

...I was constantly deleting

"";//

and re-adding for each toggle. Now I have changed to this...

public static string MyString = "";//*/@"DEBUG VALUE";

...now I just need to add/remove

/*

each time to toggle the value...

public static string MyString = /*"";//*/@"DEBUG VALUE";

result!

...and I don't want to hear about your #DEBUG comments

My opinions are right, and yours are wrong! (or at least that is my opinion)

MatchList

Timothy CIAN — Mon, 01 Aug 2011 20:22:00 GMT

    ///
     <summary>

    ///
     Compares two lists to ensure that they match without duplication.

    ///
     </summary>

    ///
     <typeparam name="T">Generic Type; string, DateTime, int etc.</typeparam>

    ///
     <param name="List1">First list to compare.</param>

    ///
     <param name="List2">Second list to compare.</param>

    ///
     <returns>

    ///
     True if the collections match and do not contain duplicates (regardless of sequence).

    ///
     False if either list is null, or they do not match.

    ///
     </returns>

    public static bool MatchList<T>(List<T> List1, List<T> List2)
{
    if (List1 == null || List2 == null) return false;
    return ((List1.Count == List2.Count) && (List1.Count == List1.Intersect(List2).Count()));
}

Did I St-St-Stutter?

AspDotNetDev — Thu, 21 Jul 2011 17:24:00 GMT

    <
    asp:PlaceHolder runat="server" ID="phPhone">
  (Code to Insert Phone Number)
</asp:PlaceHolder>

I still use hungarian notation when naming ASP.NET server controls. I hope my coworkers don't think I have a speech im... imp... imped... a speech problem.

Martin Fowler wrote:
Any fool can write code that a computer can understand. Good programmers write code that humans can understand.

Useful thingy

Jacek Gajek — Tue, 05 Jul 2011 11:02:00 GMT

I have just noticed that in the .NET 4.0 the Enum.HasFlag(Enum)[^] method was introduced. Not much clever from my side, but I rarely put a dot after enum's member so I could notice the new feature.

Greetings - Jacek