Fastest way to remove white spaces in string

Question

I\'m trying to fetch multiple email addresses seperated by \",\" within string from database table, but it\'s also returning me whitespaces, and I want to remove the whitesp

Answer 1

string input =Yourinputstring;
string[] strings = input.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
foreach (string value in strings)
{
   string newv= value.Trim();
   if (newv.Length > 0)
   newline += value + "\r\n";
}

Answer 2

string s = " Your Text ";

string new = s.Replace(" ", string.empty);

// Output:
// "YourText"

Answer 3

I would build a custom extension method using StringBuilder, like:

public static string ExceptChars(this string str, IEnumerable<char> toExclude)
{
    StringBuilder sb = new StringBuilder(str.Length);
    for (int i = 0; i < str.Length; i++)
    {
        char c = str[i];
        if (!toExclude.Contains(c))
            sb.Append(c);
    }
    return sb.ToString();
}

Usage:

var str = s.ExceptChars(new[] { ' ', '\t', '\n', '\r' });

or to be even faster:

var str = s.ExceptChars(new HashSet<char>(new[] { ' ', '\t', '\n', '\r' }));

With the hashset version, a string of 11 millions of chars takes less than 700 ms (and I'm in debug mode)

EDIT :

Previous code is generic and allows to exclude any char, but if you want to remove just blanks in the fastest possible way you can use:

public static string ExceptBlanks(this string str)
{
    StringBuilder sb = new StringBuilder(str.Length);
    for (int i = 0; i < str.Length; i++)
    {
        char c = str[i];
        switch (c)
        {
            case '\r':
            case '\n':
            case '\t':
            case ' ':
                continue;
            default:
                sb.Append(c);
                break;
        }
    }
    return sb.ToString();
}

EDIT 2 :

as correctly pointed out in the comments, the correct way to remove all the blanks is using char.IsWhiteSpace method :

public static string ExceptBlanks(this string str)
{
    StringBuilder sb = new StringBuilder(str.Length);
    for (int i = 0; i < str.Length; i++)
    {
        char c = str[i];
        if(!char.IsWhiteSpace(c))
            sb.Append(c);
    }
    return sb.ToString();
}

Answer 4

You should consider replacing spaces on the record-set within your stored procedure or query using the REPLACE( ) function if possible & even better fix your DB records since a space in an email address is invalid anyways.

As mentioned by others you would need to profile the different approaches. If you are using Regex you should minimally make it a class-level static variable:

public static Regex MultipleSpaces = new Regex(@"\s+", RegexOptions.Compiled);

emailAddress.Where(x=>{ return x != ' ';}).ToString( ) is likely to have function overhead although it could be optimized to inline by Microsoft -- again profiling will give you the answer.

The most efficient method would be to allocate a buffer and copy character by character to a new buffer and skip the spaces as you do that. C# does support pointers so you could use unsafe code, allocate a raw buffer and use pointer arithmetic to copy just like in C and that is as fast as this can possibly be done. The REPLACE( ) in SQL will handle it like that for you.

Answer 5

There are many diffrent ways, some faster then others:

public static string StripTabsAndNewlines(this string str) {

    //string builder (fast)
    StringBuilder sb = new StringBuilder(str.Length);
    for (int i = 0; i < str.Length; i++) {
        if ( !  Char.IsWhiteSpace(s[i])) {
            sb.Append();
        }
    }
    return sb.tostring();

    //linq (faster ?)
    return new string(str.ToCharArray().Where(c => !Char.IsWhiteSpace(c)).ToArray());

    //regex (slow)
    return Regex.Replace(str, @"\s+", "")

}

Answer 6

emailaddress.Replace("  ", string.empty);