searching some string in c#

You will have to use Regex for this. You cannot use Contains, since it won't take into consideration case-insensitivity and match whole word pattern. Use this instead:

string text = "James bond";

// this will return true  
bool result = Regex.IsMatch(text, "\\bjames\\b", RegexOptions.IgnoreCase);

// this will return false   
bool result = Regex.IsMatch(text, "\\bjame\\b", RegexOptions.IgnoreCase);

In the Regex formats, the above \bs will match an alphanumeric-to-nonalphanumeric boundary (or vice-versa). In this case, this ensures that you will be matching james or jame as a whole word and not a partial word.

You can use Split to separate a string into parts that are separated. Ex:

string[] items = "James Bond".Split(' ');
// items == { "James", "Bond" }

You can use ToLower to prevent case senstivity. Ex:

string lower = "James Bond".ToLower();
// lower == "james bond"

You can use StartsWith to determine if a string starts with some substring. Ex:

bool startsWithJame = "James Bond".StartsWith("Jame");
// startsWithJame == true

Using them all together:

bool anyWordStartsWith_jame_NoCaseSensitivity =
   "James Bond"
   .ToLower()
   .Split(' ')
   .Any(str => str.StartsWith("jame"));
// anyWordStartsWith_jame_NoCaseSensitivity == true

Use a regular expression. For an example see:

http://msdn.microsoft.com/en-us/library/ms228595%28v=vs.80%29.aspx

here is is matching when "cow" is found anywhere inside the string. In your case it would be "Jame".

you can use Contains method to search:

string[] names = new string[] { "joe", "bob", "chris" };
if(names.Contains("james")){
    //code
}

You can do it with Regular Expression using word boundaries. The following code will show you how you can match using a case-insensitive search and NOT have false positives with things like "jame". It works anywhere in a given string.

    static void Main(string[] args)
    {
        string name_to_match = "James Bond";
        string word_to_find = "james";
        string word_to_not_find = "jame";

        string patternToFind = string.Format(@"\b{0}\b", word_to_find);
        string patternToNotFind = string.Format(@"\b{0}\b", word_to_not_find);

        Regex regexToFind = new Regex(patternToFind, RegexOptions.IgnoreCase);
        Regex regexToNotFind = new Regex(patternToNotFind, RegexOptions.IgnoreCase);

        bool foundNameExpected = regexToFind.IsMatch(name_to_match);
        bool foundNameNotExpected = regexToNotFind.IsMatch(name_to_match);
    }

In this case, the boolean foundNameExpected will be true (because we expect "james" to match "James" in "James Bond"), however foundNameNotExpected will be false (because we do not want "jame" to match "James").