How can I check if a string is a number?

I'd like to know on C# how to check if a string is a number (and just a number).

Example :

141241   Yes
232a23   No
12412a   No

and so on...

Is there a specific function?

Solution 1:

Look up double.TryParse() if you're talking about numbers like 1, -2 and 3.14159. Some others are suggesting int.TryParse(), but that will fail on decimals.

string candidate = "3.14159";
if (double.TryParse(candidate, out var parsedNumber))
{
    // parsedNumber is a valid number!
}

EDIT: As Lukasz points out below, we should be mindful of the thread culture when parsing numbers with a decimal separator, i.e. do this to be safe:

double.TryParse(candidate, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out var parsedNumber)

Solution 2:

If you just want to check if a string is all digits (without being within a particular number range) you can use:

string test = "123";
bool allDigits = test.All(char.IsDigit);

Solution 3:

Yes there is

int temp;
int.TryParse("141241", out temp) = true
int.TryParse("232a23", out temp) = false
int.TryParse("12412a", out temp) = false

Hope this helps.

Solution 4:

Use Int32.TryParse()

int num;

bool isNum = Int32.TryParse("[string to test]", out num);

if (isNum)
{
    //Is a Number
}
else
{
    //Not a number
}

MSDN Reference

Solution 5:

Use int.TryParse():

string input = "141241";
int ouput;
bool result = int.TryParse(input, out output);

result will be true if it was.