Check if a string has only numbers in C?

Question

I\'m trying to write a simple code to check if a string only has numbers in it. So far it\'s not working, any help would be appreciated.

#include          


        

Answer 1

You have an error in the for loop - for(i = 0 ; i <= numbers ; ++i)

numbers is pointer and the comparison of it with integer is forbidden. Correct Code -

#include 
#include 
#include 

int main()
{
   char numbers[10];
   int i, correctNum = 0;

    scanf("%s", numbers);

    for(i = 0 ; i < strlen(numbers) ; ++i)
    {
       if(!(numbers[i]>='0' && numbers[i]<='9'))
       {
           correctNum = 1;
            break;
       }
    }

    if(correctNum == 1)
    {
         printf("That number has a char in it. FIX IT.\n");
     }
   else
    {
        printf("All numbers. Good.\n");
    }
    return 0;
 }