Switch - Case char problem

[mrcdlgc]

Hi everyone. I have a problem with switch - case structure. Actually , this program almost works as i want , but the only problem is that if smo enters a character as a question number , the program closes down . However , i just want to see the "ERROR.. " message when whatever i enter except for [1 . . . 10] . Is there anyone helping me ?

#include <stdio.h>
#include <conio.h>

int main (void)
{
      
      int qnumber,i;

        
             for (i=0;i<1000;i++) {
            
            printf("Please enter the question number : ");
            scanf ("%d",&qnumber);
            
            switch (qnumber) {
                   
                   case 1:
                        printf ("Question 1\n");
                        continue;
                   case 2:
                        printf ("Question 2\n");
                        continue;
                   case 3:
                        printf ("Question 3\n");
                        continue;
                   case 4:
                        printf ("Questin 4\n");
                        continue;
                   case 5:
                        printf ("Question 5\n");
                        continue;
                   case 6:
                        printf ("Question 6\n");
                        continue;
                   case 7:
                        printf ("Question 7\n");
                        continue;
                   case 8:
                        printf ("Question 8\n");
                        continue;
                   case 9:
                        printf ("Question 9\n");
                        continue;
                   case 10:
                        printf ("Question 10\n");
                        continue;
                   default:
                        printf ("ERROR!! There is no question like this.\n");
                        continue;
                           
                   
 
                   }
            
}
      
      getch ();
      return 0 ;

      }

[Salem]

You can't type in letters to scanf "%d"

It would go something like this

int r;
if ( (r=scanf("%d",&qnumber)) == 1 ) {
    // do your thing
} else if ( r == 0 ) {
  printf("That's not a number\n");
  int ch;
  // this throws away the garbage line of input
  while ( (ch=getchar()) != EOF && ch != '\n' ) { }
} else {
  printf("End of file, or file error\n");
}

[mrcdlgc]

Thanks a lot , but now i have another problem about this code. Now , if i enter "1a" as a question number , the program says both "Question 1" and "That's not a number" . In this situation , it should say "that's not a number". I can't do that. By the way , i can't understand

while ( (ch=getchar()) != EOF && ch != '\n' ) { }

this part of code. Could you explain it ?

[Salem]

> this part of code. Could you explain it ?
I did - with this comment.
// this throws away the garbage line of input

I suggest reading the manual page for getchar() to begin with.

> Now , if i enter "1a" as a question number , the program says both "Question 1" and "That's not a number"
If you want to validate a whole line, the best thing to do is read a line using fgets, then parse it with sscanf.

Say

char buff[BUFSIZ];   // look it up
while ( fgets( buff, BUFSIZ, stdin ) != NULL ) {  // look it up
   int a;
   char c;
   if ( sscanf( buff, "%d%c", &a, &c ) == 2 && c == '\n' ) {
      // an integer, a newline - nothing more, nothing less
   } else {
      // error
   }
}

[mrcdlgc]

Thank you very much