Is there a .NET equivalent to C's atoi function?

Question

If I have a string like:

"26 things"

I want to convert it to 26. I just want the integer at the beginning of the string.

If I was using C, I'd just use the atoi function. But I can't seem to find anything equivalent in .NET.

What's the easiest way to grab the integer from the beginning of a string?

Edit: I'm sorry I was ambiguous. The answers that look for a space character in the string will work in many circumstances (perhaps even mine). I was hoping for an atoi-equivalent in .NET. The answer should also work with a string like "26things". Thanks.

Answer 1

This looks sooo beautiful:

string str = "26 things";
int x = int.Parse(str.TakeWhile(ch => char.IsDigit(ch)).Aggregate("", (s, ch) => s + ch));

And, the boring solution for anyone who really wants atoi:

[System.Runtime.InteropServices.DllImport("msvcrt.dll", CallingConvention = CallingConvention.Cdecl)]
private static extern int atoi(string str);

Answer 2

This should work (edited to ignore white-space at the begining of the string)

int i = int.Parse(Regex.Match("26 things", @"^\s*(\d+)").Groups[1].Value);

If you are worried about checking if there is a value you could do the following to give you a -1 value if there is no integer at the begining of the string.

Match oMatch = Regex.Match("26 things", @"^\s*(\d+)");
int i = oMatch.Success ? int.Parse(oMatch.Groups[1].Value) : -1;

Answer 3

You could use Int32.Parse(stringVal.Substring(0, stringVal.indexOf(" "))

Answer 4

one way would be

string sample = "26 things";
int x = int.Parse(sample.Substring(0, sample.IndexOf(" ")));

Answer 5

The direct equivalent is int.Parse(string) but I'm not entirely sure if that will take just the starting number.

Answer 6

You can call Val in the Microsoft.VisualBasic.Conversion namespace. In your scenario it should print "26". I don't know if it's 100% compatible in toher scenarios though. Here's a link to the specification.

http://msdn.microsoft.com/en-us/library/k7beh1x9%28VS.71%29.aspx

Answer 7

If you want only whole number

public String GetNumber (String input)
{
    String result = "";
    for (Int32 i = 0; i < input.Length; i++)
    {
        if (Char.IsNumber(input[i]))
        {
            result += input[i];
        }
        else break;
    }
    return result;
}

Answer 8

Try this:

int i = int.Parse("26 things".Split(new Char[] {' '})[0]);

Answer 9

I can think just in something like this:

    public static string Filter(string input, string validChars) {
        int i;
        string result = "";
        for (i = 0; i < input.Length; i++) {
            if (validChars.IndexOf(input.Substring(i, 1)) >= 0) {
                result += input.Substring(i, 1);
            } else break;
        }
        return result ;
    }

And call it :

Filter("26 things", "0123456789");

Answer 10

You've got to split the string and then parse it:

var str = "26 things";
var count = int.Parse(str.Split(' ')[0]);