Thread: sscanf() string version question

I'm trying to get this code to read errors that are not positive integers. Right now if you type 50394e,for example, it won't catch the "e" as an error. I think the sscanf line has to change the string it's reading to only include positive intergers, but I'm not sure what to change it too. Minor help would be appreciated.

Thanks,
mattflick

Code:

#inlcude <stdio.h>

int main(void)

char    line[MAXLINE];
int       error, n;

do  {
      printf("Input a positive integer:   ");
      fgets(line, MAXLINE,  stdin);
      errors = sscanf(line,  "%d", &n)  ! = 1  | | n <= 0;
      if (error)
         printf("\nERROR: Do it again.\n");
} while (error);

It was good to see it done differently just for my experience and thanks for the help.

I was working on the same thing. I tried isdigit and couldnt seem to get the logic quite right. Thanks to your advice, I solved my problem this way:

Code:

#include <stdio.h>
#include <ctype.h>
#define MAXLINE 12
int get_int(int *result)
{
   char c, line [MAXLINE]; // Initialize function variables
   printf("Input a positive integer with a maximum of %d digits:  ",MAXLINE); 
   return fgets(line, MAXLINE, stdin) && !isspace(*line) && //uses fgets to return only a positive integer
          sscanf(line, "%d%c", result, &c) == 2 && (c == '\n' || c == '\0') &&
          *result >= 0;
   
}

int main(void)
{
   int n; //Initlaizes the n variable
   
//SELF DOCUMENTATION BEGIN
   printf("This program will take a line from the keyboard \nand print ONLY if the input is a valid positive integer.\n\n"); 
//SELF DOCUMENTATION END

while( !get_int(&n)){ // While function get_int does not equal a positive integer
	   fputs("\nERROR: DO IT AGAIN!\n\n", stdout);//  Looping printed error message
	   fflush(stdout);}

   printf("Your positive integer is: %d\n", n);
   return 0;
}