c# if String Contains 2 "hallo"

Question

Possible Duplicate:
How would you count occurences of a string within a string (C#)?

I want to check if a String contains 2 things..

String hello = "hellohelloaklsdhas";

if hello.Contains(*hello 2 Times*); -> True

How can I solve this?

Answer 1

You could use a regex :)

return Regex.Matches(hello, "hello").Count == 2;

This matches the string hello for the pattern "hello" and returns true if the count is 2.

Answer 2

Regular expressions.

if (Regex.IsMatch(hello,@"(.*hello.*){2,}"))

I guess you meant "hello", and this will match a string with at least 2 "hello" (not exactly 2 "hello")

Answer 3

public static class StringExtensions
{
    public static int Matches(this string text, string pattern)
    {
        int count = 0, i = 0;
        while ((i = text.IndexOf(pattern, i)) != -1)
        {
            i += pattern.Length;
            count++;
        }
        return count;
    }
}

class Program
{
    static void Main()
    {
        string s1 = "Sam's first name is Sam.";
        string s2 = "Dot Net Perls is about Dot Net";
        string s3 = "No duplicates here";
        string s4 = "aaaa";

        Console.WriteLine(s1.Matches("Sam"));  // 2
        Console.WriteLine(s1.Matches("cool")); // 0
        Console.WriteLine(s2.Matches("Dot"));  // 2
        Console.WriteLine(s2.Matches("Net"));  // 2
        Console.WriteLine(s3.Matches("here")); // 1
        Console.WriteLine(s3.Matches(" "));    // 2
        Console.WriteLine(s4.Matches("aa"));   // 2
    }
}

Answer 4

You can use a regex, and check the length of the result of Matches function. If it's two you win.

Answer 5

new Regex("hello.*hello").IsMatch(hello)

or

Regex.IsMatch(hello, "hello.*hello")

Answer 6

If you use a regular expression MatchCollection you can get this easily:

MatchCollection matches;

Regex reg = new Regex("hello"); 

matches = reg.Matches("hellohelloaklsdhas");
return (matches.Count == 2);

Answer 7

IndexOf

You can use the IndexOf method to get the index of a certain string. This method has an overload that accepts a starting point, from where to look. When the specified string is not found, -1 is returned.

Here is an example that should speak for itself.

var theString = "hello hello bye hello";
int index = -1;
int helloCount = 0;

while((index = theString.IndexOf("hello", index+1)) != -1)
{
    helloCount++;
}

return helloCount==2;

Regex

Another way to get the count is to use Regex:

return (Regex.Matches(hello, "hello").Count == 2);

Answer 8

IndexOf:

int FirstIndex = str.IndexOf("hello");
int SecondIndex = str.IndexOf("hello", FirstIndex + 1);
if(FirstIndex != -1 && SecondIndex != -1)
{
  //contains 2 or more hello
}
else
{
   //contains not
}

or if you want exactly 2: if(FirstIndex != -1 && SecondIndex != -1 && str.IndexOf("hello", SecondIndex) == -1)