Question

don't understand why this code outputs 3. Why doesn't it output 32??

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

int main()
{
printf("%d\n", parseint("32"));
return 0;
}

int parseint(char *str) {
int i=0;
while(str[i] != '\0'){
return (str[i] - '0');
i++;
}
return 1;   
}

Answer 1

your code is:

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

int main()
{
printf("%d\n", parseint("32"));
return 0;
}

int parseint(char *str) {
int i=0;
while(str[i] != '\0'){
return (str[i] - '0');
i++;
}
return 1;   
}

return breaks a loop and returns from function.return statement must be last statement to be executed,code after return statement never be executed.

It gives output 3,because first i=0 and it enters while loop and see return statement so it breaks a loop and returns with first letter of string '3' and prints in main method.it never come back.

Modified code is:

#include <stdio.h>
#include <ctype.h>
int i;                      //global variable.
int main()
{   char s[]="32";         //here any string
   i=0;
   while(s[i]!='\0'){
       printf("%d\n", parseint(s));
       i++;
   }
return 0;
}
int parseint(char *str) {
     return (str[i] - '0');
     return 1;
}

Output:

3

2