#include <ctype.h>
#include <stdio.h>

   /* atoi:  convert s to integer; version 2 */
   int atoi(char s[])
   {
       int i, n, sign;

       for (i = 0; isspace(s[i]); i++)  /* skip white space */
           ;
       sign = (s[i] == '-') ? -1 : 1;
       if (s[i] == '+' || s[i] == '-')  /* skip sign */
           i++;
       for (n = 0; isdigit(s[i]); i++)
           n = 10 * n + (s[i] - '0');
       return sign * n;
   }
main()
{
int n;
n=atoi("        -56 ");
printf("n=%d\n",n);


}