How to check if string is a number in C#

Question

In WinForm I need to check if the value in the TextBox is a number or not.

In PHP there is is_numeric function. Is something similar available in .NET?

@JustinNiessner - The OP is looking for a function similar to PHP's [`is_numeric`](http://php.net/manual/en/function.is-numeric.php). The linked answer does not provide some of the more advanced capabilities requested. — JDB, Apr 29 '13 at 21:07
I'm satisfied with the link. No need to reopen. I just hope I'll be able to delete the question in two days:) — user850010, Apr 29 '13 at 21:17
I just felt annoyed by the fact that all the C# ninjas jumped into Int32.TryParse without checking what PHP is_numeric function covers.. — G.Y, Apr 29 '13 at 21:21
As this question is closed, I've added my answer to the linked question. It actually answers the stated question: replicating `is_numeric`. See http://www.stackoverflow.com/a/16303109/211627 (Even if the OP is satisfied with the linked question/answer, replicating `is_numeric` is still an interesting challenge) — JDB, Apr 30 '13 at 15:17
Thanks Cyborg37. I totally forgot about possible signs, digits in the numbers. upvoted your answer. — user850010, May 01 '13 at 16:55

score 2 · Answer 1 · answered Apr 29 '13 at 21:04

2

I'd use TryParse to check

string str = "123";
int i;

if (int.TryParse(str, out i))
{
    // it's an int
}

you should be able to do similar with other types, such as double

answered Apr 29 '13 at 21:04

If you check the documentation for PHP's `is_numeric`, you'll find that `"0x4a"`, `"7.9"` and `"+1.2e3"` should also return `true`. – JDB Apr 29 '13 at 21:12

score 2 · Answer 2 · answered Apr 29 '13 at 21:05

2

int val;
bool parsed = Int32.TryParse(input_str, out val);

Gives you both if it's a valid int and the result of parsing it as int as well (in val)

answered Apr 29 '13 at 21:05

J0HN

Kimtho6 · Answer 3 · 2013-04-29T21:11:03.140

1

int number;
string str="!23";
if(int.TryParse(str, out number))
{
    //do something
}

if you are 100% sure its an int you can use:

int.Parse(str);

or

Convert.ToInt32(str);

it will cast an execption if its not an int

edited Apr 29 '13 at 21:11

answered Apr 29 '13 at 21:05

Kimtho6

score 0 · Answer 4 · answered Apr 29 '13 at 21:05

0

double.tryparse will allow you to check the string.

answered Apr 29 '13 at 21:05

rerun

4 Answers4