Could someone help me simplify some lines

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Hello! First of all I would like to thank every single one of you who has helped me so far learning and understanding all the questions I've been asking.

Now.. I have this software that I am working on (its working) and its really simple, well I understand 85% of it the rest I got help with but he didnt explain it very well..

What I need help with is simplify some code (Dummy it down) and explain what it means. Everything with the comment //This I dont really understand, so if possible, could someone comment it out to explain why its there and what it exactly does.

Thank you so much! :D

C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Arrays
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        int[] numbers = new int[5];
        List<int> numbersList = new List<int>();
        string text = System.IO.File.ReadAllText(@"C:\Users\Developer\Documents\Visual Studio 2015\Projects\Arrays\hash.txt");
        string[] displayStringArrays = null; //This

        private void Form1_Load(object sender, EventArgs e)
        {
            //numbers[0] = 12;
            //numbers[1] = 10;
            //numbers[2] = 25;
            //numbers[3] = 10;
            //numbers[4] = 15;
            //numbersList.Add(23);
            //numbersList.Add(32);
            //numbersList.Add(35);
        }
        //Array Print
        private void button1_Click(object sender, EventArgs e)
        {
            displayArrays.Text = listText.Text;
        }
        //List Print
        private void button2_Click(object sender, EventArgs e)
        {
            displayStringArrays = text.Split('\n').ToArray(); //This
            foreach (var item in displayStringArrays) //This
            {
                displayArraysString.Text += item;

                if (listText.Text == item.Substring(0, item.Length - 1) || listText.Text == item) //This
                {
                    MessageBox.Show("Found a match!");
                    return;
                }
                else
                {
                    //Something.
                }
            }

        }

        private void displayArraysString_TextChanged(object sender, EventArgs e)
        {

        }
    }
}

What I have tried:

I've tried googleing but no "simple" answers were found

Posted 10-May-16 4:05am

BladeLogan

Updated 10-May-16 4:39am

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CHill60 · Accepted Answer · 2016-05-10T04:23:00

Solution 1

C#

string[] displayStringArrays = null;

Is declaring a array of strings called displayStringArrays and initialising the value of the array to null - i.e. it has been declared but has no value (yet). The = null is not really necessary.

C#

displayStringArrays = text.Split('\n').ToArray();

This line is taking the contents of the variable text and splitting it into separate strings wherever it finds a carriage return/line feed ('\n'). It places each of the strings into the array that was declared earlier.

C#

foreach (var item in displayStringArrays)

Is saying - execute the following block of statements (between the matching braces { and }) once for each one of the strings in the array. It's similar to using

C#

for (int i =0; i < displayStrings.Length; i++)

C#

if (listText.Text == item.Substring(0, item.Length - 1) || listText.Text == item)

This is comparing the Text property of a control called listTextto the string that is currently the subject of the foreach loop - it will be checked against all of the strings in the array one by one. The comparison is checking to see if the string in the array exactly matches the text in the control OR (||) if the text in the control starts with the same text as the string (Substring)

Posted 10-May-16 4:23am

CHill60

Updated 10-May-16 4:25am

v2

Comments

BladeLogan 10-May-16 10:25am

Thank you so much that made things alot more clear! You said that " string[] displayStringArrays = null; " isnt necessary, could I remove the whole line?

CHill60 10-May-16 10:28am

No - you can't remove it as you are using the variable across several methods and it has to be declared before it can be used. If you just declare it within each method, you will actually get a different variable - check out Variable and Method Scope in Microsoft .NET[^].

Just remove the =null bit ... i.e. string[] displayStringArrays;

Sergey Alexandrovich Kryukov 10-May-16 10:53am

How do you know it's '\n'? This part is potentially incorrect.
—SA

CHill60 10-May-16 10:58am

Well the line of code the OP was questioning was the overload of Split that takes a single parameter - a char array. In this instance an array with a single entry '\n'. Or am I missing something?

Sergey Alexandrovich Kryukov 10-May-16 11:11am

I see absolutely no evidence that this is not '\n', '\r' or a combination of anything. It depends on the origin of data, such as platform, so cross-platform System.Environment.NewLine can be used. But it only works if the file is created on the same platform, which is likely, in this case.
—SA

CHill60 10-May-16 11:35am

I get the cross platform stuff and the .NewLine ... but what I'm not getting is where my solution is potentially incorrect. I didn't write the code - I was explaining what it does.
The code that the OP has, explicitly attempts to split the strings with '\n' - .Split('\n'). I felt I would be delinquent if I did not explain what that character meant. F-ES Sitecore did the same thing, but in more detail.

I really don't understand what the inaccuracy is in my solution (and by extension, the inaccuracy that must also exist with Solution 2)

Sergey Alexandrovich Kryukov 10-May-16 11:39am

It is potentially incorrect, because, for example, on Windows, you will get \r\n separators on input. With your kind of split, you will have lines contaminated with remaining \r. And so on...
Look at the split of Solution 2; it will give accurate results, in practice, because I don't know other separators except '\n' and '\r'...
—SA

CHill60 10-May-16 12:05pm

That's fine ... but I have to state yet again - I did not write the code. I only explained to the OP what *their* code was doing.
If you want to critique the code then the comments would be better addressed to the OP - who presumably will know what the content of the text is.

Sergey Alexandrovich Kryukov 10-May-16 12:34pm

I understand. But yet, you wrote the like of that code in your answer. You did not disclaimed that it's not yours, or wrong, or something like that.

Here is one your mistake: "it finds a carriage return/line feed ('\n')." No, it doesn't. '\n' is line feed, but carriage return is '\r'. Can you see the point?

—SA

CHill60 10-May-16 17:14pm

Now I finally see your point. Yes I was wrong to use the words "carriage return / line feed". I thought it was patently obvious that I was quoting the question. ..I'll make more effort in future to make it more obvious. A little more effort on both sides perhaps

BladeLogan 10-May-16 12:49pm

I dont know if this makes a difference, if it makes the code better or worse but im pulling all the MD5 hashes from a textfile on my computer as you can see in the code and that textfile includes 26.000 hash codes which looks like this.

49a08a45bc2d15eb6a9e74604e4f31eb
52c7cea625d4d0f194ebe2a1b22c8e2d
74696157df46be644a80019a446f797b
8df88fd53b0b6e11f6922f6c1d6357b5
aa8e08e7dc76e178d83bd640e2400032
b722f61b331b4d4f4ca3f1d296345ced
f3148607545cb31dfb3442e03433076c
337f548e7d4991acb3886ed528833e27

My friend told me to store them in memory instead of using a text document

F-ES Sitecore · Accepted Answer · 2016-05-10T04:39:00

Have a read of these

Arrays Tutorial (C#)[^]
String.Split Method (System)[^]
String.Substring Method (Int32, Int32) (System)[^]

C#

string[] displayStringArrays = null;

This means that displayStringArrays is an array of strings, however it is simply being defined at this point, it doesn't actually contain an array of strings just yet. The other thing of note is that at this point we don't know the size of the array either, we just know that this variable can now contain an array of strings in the future.

C#

displayStringArrays = text.Split('\n').ToArray(); //This

First off the code above doesn't need the ToArray

C#

displayStringArrays = text.Split('\n'); //This

Split converts a single string into an array of strings using the character you supply as the separator. So if text was "abcabcabcdef" then Split('c') on that text would result in an array like this

C#

displayStringArrays[0] = "ab";
displayStringArrays[1] = "ab";
displayStringArrays[2] = "ab";
displayStringArrays[3] = "def";

So when you Split('\n'), \n is the code for new line, you are taking a chunk of text that has multiple lines and creating an array where each element in that array is a line. So if the text was;

how now
brown cow

you'd have an array like

C#

displayStringArrays[0] = "how now";
displayStringArrays[1] = "brown cow";

C#

foreach (var item in displayStringArrays)

That line will cause the code in the { } block to loop once for each item in your array, so the first iteration "item" will be displayStringArrays[0], the second iteration will be displayStringArrays[1] and so on.

Basically what the code is doing is splitting the text in the file into an array of lines, and processing each line at a time with that line being in "item".

C#

if (listText.Text == item.Substring(0, item.Length - 1) || listText.Text == item)

That's not good code. The "||" means "or", so if the statement to the left or it or the statement to the right is true the "if" evaluates as true. The statement to the right (listText.Text == item) is straightforward, it means if the text in that textbox is the same as "item".

The code to the left is comparing the text box with the substring of "0, length-1" of "item". That means starting at character 0 (the first) and going to the length of item minus 1, ie the second but last character. So if "item" is "Hello" then that substring is

"Hell"

The length of Hello is 5, so starting at the first character and taking the 4 characters you get "Hell"

So it item is "Hello" and listText.Text is "Hell" + <any character> then that will resolve to true. So if listText is any of these;

Hella
Hellb
Hellc
Helld
Helle

then

C#

listText.Text == item.Substring(0, item.Length - 1)

will resolve to true. I assume that logic was done for a reason and I am going to further assume it is to capture either a trailing space, so a trailing carriage return. As we can't see your data we don't know, but that is my guess. If that Is right then there are better ways of handling that, eg changing the Split to this

C#

displayStringArrays = text.Split(new char[]{'\r','\n'}, StringSplitOptions.RemoveEmptyEntries);

If the code is there to ignore trailing spaces then you can use Trim()

C#

if (listText.Text.Trim() == item.Trim())

As it is the code has introduced a bug that is going to give unintended results. Eg the line might be

"Mend"

and your compare text might be "Men" and that is going to register a match when it isn't.