C#: whether string is number or not

PRR

i had come across this kinda puzzle... there a function which takes in a input in form of string.. the string can be as long as required.. (may cause overflow exception).. its required to test whether the string is numeric or not...numeric includes int,long, currency. i first thought of regular expression... or at the basic maybe try parsing to right type.... Even if you leave out currency... is there a way of doin this? is there something in .net that i m missing?

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private bool isNumber(string s)

        {

            bool num = true;

            try

            {

                // Code to test whether s can be a number (integer, double or maybe currency)

                // the first way is int.Parse Int64.Parse(s); or regular expression
 
            }

            catch (Exception e)            

            {

                num = false;

            }
 
            return num;
 
        }

pootle

Hi,

No, you are not missing something. Shameful isn't it? You would expect this kind of simple operation to be included somewhere in such a rich framework...

You have both of the common ways to solve this problem. Just for completeness, the regular expression approach (my personal preference) can be done using the following:

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 private static Regex _isNumber = new Regex(@"^\d+$");

public static bool IsNumeric(string inputData) {

   Match m = _isNumber.Match(inputData);

   return m.Success;

}

You could also make incremental char comparisons within a for loop testing if each char of the string is a number.

Regards.

PRR

ya i would too go with regular expression.... i had also written a function for conversion... (again a long string)... i thought maybe there's a shortcut way of doing it...thx for ur reply ...

tlhintoq

try
{
int x = Convert.ToInt64(stringVariable);
Catch
{
// then it isn't a number
}

PRR

Quote:

Originally Posted by tlhintoq

try
{
int x = Convert.ToInt64(stringVariable);
// wat if i give //99999999999999999999999999999999999999999999999999 999999999
//12345667890994645645656234234243245656465645645
//45345435345345345345
// this will cause overflow.... and wat abt double,
Catch
{
// then it isn't a number
}

i was lookin at something that can recognize any number as number... like of any length... n also double... also if possible currency or other standardized data ... its more like a puzzle program...

cloud255

Quote:

Originally Posted by dirtbag

i was lookin at something that can recognize any number as number... like of any length... n also double... also if possible currency or other standardized data ... its more like a puzzle program...

Nothing can hold infinite length data, so you need to put a maximum length on your input control or trim the user input. I suppose you could do a 'nested try catch' where you try to parse to each numeric type until it succeeds or in the final catch you know it is not a number.

Plater

Double.TryParse() is probably your best bet.
There should be overloads(at least on .Parse() there are) to dictate that a "$" might be in the number.

C#: whether string is number or not

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