Counting A Character

Question

3.33/5 (2 votes)

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hi guys i have a textbox and textBox1.Text is for example: Jack#Alex#Marlo#Jimmy#Bob

now i wanna find out how many [#] is there in the textbox, i know its 4 [#] in that sentence but dont know how to get that count
plzzzzzz help me

Posted 27-Nov-14 11:15am

Member 10540973

Updated 27-Nov-14 11:32am

Maciej Los

v2

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5 solutions

Solution 4

Here are two unconventional techniques which will get the count of the # charater:

C#

string theString = @"Jack#Alex#Marlo#Jimmy#Bob";

int LengthReplaceCnt = theString.Length - theString.Replace("#","").Length;

int SplitGetUpperBoundCnt = theString.Split('#').GetUpperBound(0);

Not sure how efficient they will be compared to the LINQ solutions.
But I believe the Length, Replace one will fare quite well.

Posted 28-Nov-14 0:31am

jaket-cp

Comments

Maciej Los 28-Nov-14 6:43am

Nice try, worth a5!
There is nothing to compare to Linq query/method.

jaket-cp 28-Nov-14 6:47am

Thanks :)
Yes I like the Linq, but sometimes you just don't know what it is doing under the hood.

Maciej Los 28-Nov-14 6:54am

;)

Solution 5

The essense of the task is simply:

C#

int count = 0 ; 
for ( int i = 0 ; i < somestring.Length ; i++ ) 
  if ( somestring [ i ] == soughtchar ) count++ ;

The Linq examples will (in some cases) copy the string, then get an enumerator, then iterate the characters, possibly copy them again, and get a count. The simple for loop will perform only the minimum operations required. And it's recognizable by nearly every developer for the last forty years.

As a general rule, avoid foreach when a for or while loop will suffice.

Furthermore, this code will port to other systems and languages much more easily; Linq won't port.

Posted 28-Nov-14 8:12am

PIEBALDconsult

Updated 6-Dec-14 13:08pm

v3

Comments

[no name] 7-Dec-14 7:51am

Quote: "As a general rule, avoid foreach when a for or while loop will suffice."
Why this? Do you have some links to read about this?
Thank you
Bruno

[EDIT]
Just found the links by myself. My 5 because your solution is smart and straight forward and does not blow up everything.
[EDIT]

PIEBALDconsult 7-Dec-14 10:32am

Thanks.

Maciej Los 12-Dec-14 17:53pm

5ed!

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Maciej Los · Accepted Answer · 2014-11-27T21:30:00

Inspired by the discussion about "unnecessary ToArray() method call", i decide to post this answer to bring more information about the "differences" between methods used in a both solutions (solution 1 and solution 2).

The most important statement is: Both solutions are equivalent and return exactly the same result!
Even if there are few differences (in a scope of code compilation and execution - see below table), it doesn't matter in this case! It might makes a difference only in case when the set of strings comparison is performed.

Solution 1	Solution 2
query syntax	method syntax
IL instructions (generated by LinqPad 4): VB IL_0001: ldstr "Jack#Alex#Marlo#Jimmy#Bob" IL_0006: stloc.0 // s IL_0007: ldloc.0 // s IL_0008: call System.Linq.Enumerable.ToArray IL_000D: ldsfld UserQuery.CS$<>9__CachedAnonymousMethodDelegate1 IL_0012: brtrue.s IL_0027 IL_0014: ldnull IL_0015: ldftn b__0 IL_001B: newobj System.Func<System.Char,System.Boolean>..ctor IL_0020: stsfld UserQuery.CS$<>9__CachedAnonymousMethodDelegate1 IL_0025: br.s IL_0027 IL_0027: ldsfld UserQuery.CS$<>9__CachedAnonymousMethodDelegate1 IL_002C: call System.Linq.Enumerable.Where IL_0031: call System.Linq.Enumerable.Count IL_0036: stloc.1 // SharpCount b__0: IL_0000: ldarg.0 IL_0001: ldc.i4.s 23 IL_0003: ceq IL_0005: stloc.0 // CS$1$0000 IL_0006: br.s IL_0008 IL_0008: ldloc.0 // CS$1$0000 IL_0009: ret	IL instructions (generated by LinqPad 4): VB IL_0001: ldstr "Jack#Alex#Marlo#Jimmy#Bob" IL_0006: stloc.0 // theString IL_0007: ldloc.0 // theString IL_0008: ldsfld UserQuery.CS$<>9__CachedAnonymousMethodDelegate1 IL_000D: brtrue.s IL_0022 IL_000F: ldnull IL_0010: ldftn b__0 IL_0016: newobj System.Func<System.Char,System.Boolean>..ctor IL_001B: stsfld UserQuery.CS$<>9__CachedAnonymousMethodDelegate1 IL_0020: br.s IL_0022 IL_0022: ldsfld UserQuery.CS$<>9__CachedAnonymousMethodDelegate1 IL_0027: call System.Linq.Enumerable.Count IL_002C: stloc.1 // cntNumberSign b__0: IL_0000: ldarg.0 IL_0001: ldc.i4.s 23 IL_0003: ceq IL_0005: stloc.0 // CS$1$0000 IL_0006: br.s IL_0008 IL_0008: ldloc.0 // CS$1$0000 IL_0009: ret
Not uses lambda expressions, but compiler changes the query expression into the equivalent Lambda expression	Uses lambda expressions, so compiler doesn't need to "change" anything.
Time of code execution: `00:00.000`	Time of code execution: `00:00.000`
Query used in this solution is equivalent to: C# int SharpCount = s.Where(c=>c=='#').Select(c=>c).Count();	Query used in this solution does not use `Select` method. C# int cntNumberSign = theString.Count(c => c == '#');

Conclusion:
There is only one (the most important) difference: first solution uses "unnecessary" Select method, but not ToArray()! ;) In both cases ToArray() method is used. In the second one, ToArray method is used indirect, because delegate method must split characters to array to be able to compare each character to '#'.

For further information, please see:
Query Syntax and Method Syntax in LINQ (C#)[^]
Lambda Expressions (C# Programming Guide)[^]

Thank you, anonymous downvoter! You've been my inspiration to take a bit deeper analysis.

BillWoodruff · Accepted Answer · 2014-11-27T11:41:00

Solution 2

C#

// using Linq

string theString = @"Jack#Alex#Marlo#Jimmy#Bob";

int cntNumberSign = theString.Count(c => c == '#');

Posted 27-Nov-14 11:41am

BillWoodruff

Comments

Maciej Los 27-Nov-14 17:53pm

I like lambda expressions ;)
+5!

BillWoodruff 27-Nov-14 17:56pm

Thanks, Maciej !

Maciej Los 27-Nov-14 17:58pm

Have you seen my answer?
I'd like to say: different ways to achieve the same ;)

BillWoodruff 27-Nov-14 19:44pm

"different ways to achieve the same:" indeed ! I wish I had the "deep inner knowledge" of what the .NET compiler produces (the IL) to be able to immediately visualize what various alternatives do, but I don't, and, at this point in my life, that deep understanding of FrameWork internals is not something I will strive/attempt to achieve. As an American would say, "I have other fish to fry," like a novel in progress, and other passions in life outside of programming.

My hypothesis would be that your example does "more work" than simply using the Count-with-a-Predicate, but, until someone with the expertise reviews the IL, I wouldn't bet on that hypothesis :)

PIEBALDconsult 6-Dec-14 19:01pm

"My hypothesis would be that your example does "more work"
"

Yes, it copies the string to another array, needlessly.

PIEBALDconsult 27-Nov-14 18:14pm

At least it doesn't use ToArray.

BillWoodruff 27-Nov-14 19:36pm

My esteemed colleague, Piebald, if you have a problem with any other person's solution, please take that up directly with them; if you have any suggestions, or criticisms, on how I can improve anything I ever post, I would consider it a gift for you to share them with me. cheers, Bill

Maciej Los 28-Nov-14 3:43am

Thank you, Bill. You're completely right. I think that PIEBALDconsult's comment is a voice of His positive opinion about your solution. But, i strongly believe He's wrong. Please, see solution 3. I explained there the differences between both solutions.

PIEBALDconsult 6-Dec-14 18:48pm

What irks me most of all about _inexperienced_ users of Linq is their overuse of certain paradigms, e.g. calling something like ToArray<char> on a string simply because they want to iterate the characters -- not realizing that a string is _already_ IEnumerable<char> .
I was pointing out that your Solution demonstrates that ToArray is not required for the task, whereas Solution 1 performs this needless copy operation. It may well not matter to this situation, but other _inexperienced_ developers will see examples such as Solution 1 and think that ToArray (etc.) is required.
I'm sure you know about cargo cult programming.

I come back to this today because of an article that uses
foreach (DataRow dataRow in dataTable.AsEnumerable().ToList())
rather than simply
foreach (DataRow dataRow in dataTable.Rows)

Animesh Datta 28-Nov-14 2:21am

simple and clear . My 5!

Maciej Los · Accepted Answer · 2014-11-27T11:29:00

Solution 1

You can use Linq[^]:

C#

string s = @"Jack#Alex#Marlo#Jimmy#Bob";

int SharpCount = (from x in s.ToArray()
    where x == '#'
    select x).Count();

    Console.WriteLine(SharpCount);

Result: 4

Posted 27-Nov-14 11:29am

Maciej Los

Updated 27-Nov-14 11:30am

v2

Comments

BillWoodruff 27-Nov-14 19:36pm

Voted #5 to counteract a very unnecessary down-vote.

Maciej Los 28-Nov-14 0:21am

Thank you,Bill.
It's quite often practice some persons to downvote someones solution without any explonation.
I'll show you the content of IL for both solutions to be able to discuss about that.

Animesh Datta 28-Nov-14 2:21am

My 5!

Maciej Los 28-Nov-14 2:23am

Thank you ;)

Counting A Character

5 solutions

Solution 3

Solution 4

Solution 5

Solution 2

Solution 1

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