left string function in C#

Question

What's the best way to return the first word of a string in C#?

Basically if the string is "hello world", I need to get "hello".

Thanks

Solution 1

You can use a combination of Substring and IndexOf.

var s = "Hello World";
var firstWord = s.Substring(0,s.IndexOf(" "));

However, this will not give the expected word if the input string only has one word, so a special case is needed.

var s = "Hello";
var firstWord = s.IndexOf(" ") > -1 
                  ? s.Substring(0,s.IndexOf(" "))
                  : s;

Solution 2

You can try:

string s = "Hello World";
string firstWord = s.Split(' ').First();

Ohad Schneider's comment is right, so you can simply ask for the First() element as there will always be at least one element.

For further info on whether to use First() or FirstOrDefault() you can learn more here

Solution 3

One way is to look for a space in the string, and use the position of the space to get the first word:

int index = s.IndexOf(' ');
if (index != -1) {
  s = s.Substring(0, index);
}

Another way is to use a regular expression to look for a word boundary:

s = Regex.Match(s, @"(.+?)\b").Groups[1].Value;

Solution 4

The answer of Jamiec is the most efficient if you want to split only on spaces. But, just for the sake of variety, here's another version:

var  FirstWord = "Hello World".Split(null, StringSplitOptions.RemoveEmptyEntries)[0];

As a bonus this will also recognize all kinds of exotic whitespace characters and will ignore multiple consecutive whitespace characters (in effect it will trim the leading/trailing whitespace from the result).

Note that it will count symbols as letters too, so if your string is Hello, world!, it will return Hello,. If you don't need that, then pass an array of delimiter characters in the first parameter.

But if you want it to be 100% foolproof in every language of the world, then it's going to get tough...

Solution 5

Shamelessly stolen from the msdn site (http://msdn.microsoft.com/en-us/library/b873y76a.aspx)

string words = "This is a list of words, with: a bit of punctuation" +
    "\tand a tab character.";
string [] split = words.Split(new Char [] {' ', ',', '.', ':', '\t' });
if( split.Length > 0 )
{
    return split[0];
}

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Comments

[Paul Ruane]

I would add a special case for if the string contains only one word, e.g. if IndexOf returns -1.