How to check whether a string is number

qiqinuinaifen128's Avatar, Join Date: Dec 2007
Light Poster
if i have a string, how do i check whether the string is number?
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technosavvy's Avatar
Contributor
look for atoi() function...
it will return zero if it is not able to convert the string passed into number..

though if you have an alphanumeric inputs (like 1234go4expert)..u should go for strtol()..

both the functions even convert the input passed into their respective numbers(if possible).
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Salem's Avatar, Join Date: Nov 2007
Ambitious contributor
You should use strtol() all the time.
atoi() for example cannot detect numeric overflow.
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technosavvy's Avatar
Contributor
completely agree..
there is another kind of case ..when input is "1234forum"
atoi() will return 1234..!!

and in case of strtol() using the third argument we can check if the function traversed the whole input or not..
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qiqinuinaifen128's Avatar, Join Date: Dec 2007
Light Poster
Thank you so much. I will try it