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I have a static class MyExtension,which has CountOf static function,this function must return number of that letters,which i wrote in string.In Main i must write like this`
string str = "hello";
     int r = str.CountOf('l');

It will print 2, because there are two 'l' letter in string.

What I have tried:

i have tried like this`
static public int CountOf(this string str,char ch)

            return str.Count();

but i know it's false,because it's return number of string
Updated 7-Feb-18 23:13pm

There are a lot of ways to do this, but the simplest is just to brute force it.
But ... this is your homework, so I'll give you no code!

1) Create a local interegr variable called count and set it to zero.
2) Use a foreach loop on the string to access each character
2.1) Inside the loop, check if the current character matches the "search for" character
2.1.1) If it matches, increment count
3) After the loop, return count
Suren97 8-Feb-18 6:21am
Thank you very much :)
OriginalGriff 8-Feb-18 6:24am
You're welcome!
You have to go through the collection of chars, compare them to input and return the count of searched letter in a string.

string str = "hello";
char input = 'l';
int counter = 0;
//method 1
foreach(char a in str)
	if(a==input) counter++; 
//counter = 2

//method 2 - linq
var result = str.Count(x=>x==input);
//result = 2
Karthik_Mahalingam 8-Feb-18 5:59am
Maciej Los 8-Feb-18 6:22am
Thank you, Karthik
Suren97 8-Feb-18 6:22am
Thank you very much :)
Maciej Los 8-Feb-18 6:22am
You're very welcome.
Please accpet my solution (green button) if it was helpful (to mark your question as answered).
Suren97 8-Feb-18 6:27am
i alredy accepted :)
Maciej Los 8-Feb-18 6:29am
Thank you ;)
You could use LINQ count, see answers here: count the number of characters in a string[^]
Suren97 8-Feb-18 6:22am
Thank you very much :)

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