beginner ?

when i type anything but a number the program starts a endless loop. what code can i write into the program to stop this ,and what causes the loop.

Code:

---

#include <stdio.h>

int main()
{

  int x;

  printf("enter a numbr 1 thru 10\n");
  scanf("%d",&x);
 
  if (x<1 || x>10)
  main();

  else
  printf("\nyou typed %d",x);

  return(0);
}

---

scanf doesn't catch the carriage return very well, so in your loop when it comes back around their is a carriage return in the buffer. This carriage return seem to remain in there and thus causes your infinite loop.

This might work better for you:

Code:

---

#include <stdio.h>

int main() {
 int x = 0;
 char junk;

 while ( x < 1 || x > 10 ) {
  printf( "enter a numbr 1 thru 10\n" );
  scanf( "%d%c", &x, &junk );
 }
 printf("\nyou typed %d",x);

 return(0);
}

---

First you'll need to check the return value of the scanf function to see if the user really entered a number:

Code:

---

if(scanf("%d", %x) != 1)
  printf("This is not a number.\nPlease try again.\n");

---

Then you'll need to get rid of the newline character, which is still in your input buffer:

Code:

---

while(getchar() != '\n') /*do nothing */;

---

Dharh, you example works on valid input but not if the user enters characters in stead of numbers. It's better to use the getchar function in a loop to remove the newline character.