How to remove leading and trailing characters from string in csharp (c#).

To remove leading and trailing characters from string in csharp (c#) we can use methods String.Trim(), String.TrimEnd() or String.TrimStart().

Samples:

originalLine = " message with space, ";
actualLine = originalLine.Trim();
DisplayMessage(originalLine, actualLine);

originalLine = " message with space, ";
actualLine = originalLine.TrimEnd();
DisplayMessage(originalLine, actualLine);

originalLine = " message with space, ";
actualLine = originalLine.TrimStart();
DisplayMessage(originalLine, actualLine);

originalLine = " message with space, ";
actualLine = originalLine.Trim(new char[] { ' ', ',' });
DisplayMessage(originalLine, actualLine);

Sometimes interesting to see implementation of C# methods.

So, let's see method String.Trim(Char[]):

// Removes a string of characters from the ends of this string. 
public String Trim(params char[] trimChars) {
    if (null==trimChars || trimChars.Length == 0) { 
        trimChars=WhitespaceChars;
    }
    return TrimHelper(trimChars,TrimBoth);
} 

and basic method TrimHelper():

private String TrimHelper(char[] trimChars, int trimType) { 
    //end will point to the first non-trimmed character on the right
    //start will point to the first non-trimmed character on the Left
    int end = this.Length-1;
    int start=0; 

    //Trim specified characters. 
    if (trimType !=TrimTail)  { 
        for (start=0; start < this.Length; start++) {
            int i = 0; 
            char ch = this[start];
            for( i = 0; i < trimChars.Length; i++) {
                if( trimChars[i] == ch) break;
            } 
            if( i == trimChars.Length) { // the character is not white space
                break; 
            } 
        }
    } 

    if (trimType !=TrimHead) {
        for (end= Length -1; end >= start;  end--) {
            int i = 0; 
            char ch = this[end];
            for(i = 0; i < trimChars.Length; i++) { 
                if( trimChars[i] == ch) break; 
            }
            if( i == trimChars.Length) { // the character is not white space 
                break;
            }
        }
    } 

    //Create a new STRINGREF and initialize it from the range determined above. 
    int len = end -start + 1; 
    if (len == this.Length) {
        // Don't allocate a new string is the trimmed string has not changed. 
        return this;
    }
    else {
        if( len == 0) { 
            return String.Empty;
        } 
        return InternalSubString(start, len, false); 
    }
} 

References:

String.Trim Method