You realize there's a built in method called TryParse that is specifically for this?

string number = "00";

int tempInteger;
if(int.TryParse(number, out tempInteger))

Just use TryParse method. It returns true if the conversion was successful, false otherwise. No exception is thrown.

The most efficient method to decide if a string is int is the Int32.TryParse method.

public static bool TryParse(
string s,
out int result
)

The 'result' parameter returns the converted number or 0 it the conversion failed. Also the method returns true on successful conversion and false when the conversion failed.

But what if the string representation of the number contains a minus sign (-) ?? That's perfectly valid for a string representation of a signed int, yet your code will not see it as a number.

I think int.TryParse() is a great method if you want to check if the string is a number or not.

string number = "3"

int outputNumber;
if(int.TryParse(number, out outputNumber)
//Do some stuff with outputNumber
else
//Not a number

How about Int32.TryParse?

Make sure to put a "break;" to exit the loop quickly. Good luck.

There is always int.TryParse

string numberString = "100";
int value;
if(int.TryParse(numberString, out value)
{
//You have a valid int
}

The only other problem with the Char.IsNumber approach is that it will only work for positive integers. "0.0" will fail as will "-0.0". Not a problem if you just want to test for integral values.

If you want to test for real values as well then double.TryParse will do the trick. You can also pass in optional localization info.

Use TryParse..

The way that I know most people tend to use for this is to use the Integer.TryParse() method.

int value = 0;
Integer.TryParse(myString, out value);

Since the method is a bool it will return true if value is a valid int, false if it is not a valid int.

int.TryParse ?

Didn't mean to dogpile, but there were no other comments visible when I wrote mine.

HI All,

Thanks for your comments. Yes I know about int.TryParse(). The only problem I had with that was that it internally uses try and catch block to find the if the number is an integer or not. Which actually brings the same problem.

But that is not a bad option. Also as many people pointed out, my function is only useful when working with positive integer number. Actually My requirement when creating the function was that only. But yes the function does has limitation.

Hi Robert,

All my comment goes through moderation, and that is why it took some time. I was a bit busy today and that is wahy it took some time for all the comment to come.

HI Sam,

Good pointer, The break should be there in the for loop when we get that the string is not a number. :-)

Some where i found this:

public static bool IsNumeric(object Expression)
{
bool isNum;
double retNum;
isNum = Double.TryParse(Convert.ToString(Expression),
System.Globalization.NumberStyles.Any,
System.Globalization.NumberFormatInfo.InvariantInfo,
out retNum);
return isNum;
}

Int32.TryParse doesn't use try/catch, it's the best and safest way to check it.