How can I tell if a value in Request.Form is a number? (C#)

Question

Suppose I must call a function with the following signature: doStuff(Int32?)

I want to pass to doStuff a value that is read from Request.Form. However, if the value passed in is blank, missing, or not a number, I want doStuff to be passed a null argument. This should not result in a error; it is a operation.

I have to do this with eight such values, so I would like to know what is an elegent way to write in C#

var foo = Request.Form["foo"];
if (foo is a number)
    doStuff(foo);
else
    doStuff(null);

Do you need to check for int, decimals etc? What does count as a number? — alexn, Jun 07 '11 at 20:41
In the example I cited, it needs to be an `Int32`, but this question applies to different numeric types. — Vivian River, Jun 07 '11 at 20:45

score 8 · Accepted Answer · answered Jun 07 '11 at 20:41

8

If you want to check whether or not it's an integer, try parsing it:

int value;
if (int.TryParse(Request.Form["foo"], out value)) {
    // it's a number use the variable 'value'
} else {
    // not a number
}

answered Jun 07 '11 at 20:41

configurator

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Paulo Santos · Answer 2 · 2011-06-08T13:38:42.323

5

You can do something like

int dummy;
if (int.TryParse(foo, out dummy)) {
   //...
}

edited Jun 08 '11 at 13:38

answered Jun 07 '11 at 20:41

Paulo Santos

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score 4 · Answer 3 · answered Jun 07 '11 at 20:42

4

Use Int32.TryParse

e.g:

var foo = Request.Form["foo"]; 
int fooInt = 0;

if (Int32.TryParse(foo, out fooInt ))     
    doStuff(fooInt); 
else     
    doStuff(null);

answered Jun 07 '11 at 20:42

Chandu

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How can I tell if a value in Request.Form is a number? (C#)

3 Answers3