How to check if a string is a number?

Question

I want to check if a string is a number with this code. I must check that all the chars in the string are integer, but the while returns always isDigit = 1. I don\'t know wh

Answer 1

Your condition says if X is greater than 57 AND smaller than 48. X cannot be both greater than 57 and smaller than 48 at the same time.

if(tmp[j] > 57 && tmp[j] < 48)

It should be if X is greater than 57 OR smaller than 48:

if(tmp[j] > 57 || tmp[j] < 48)