getchar() stopping after printing one value

Question

Function of the code: The function of my code is pretty simple. It converts a phone number with numbers into a phone number.

#include <stdio.h>

main(){

  char num;

  printf("Please enter a phone number with letters to be converted into a phone number: \n");

  while ((num = getchar()) != '\n') {
    switch(num){
      case 'A': case 'B': case 'C': printf("2"); break;
      case 'D': case 'E': case 'F': printf("3"); break;
      case 'G': case 'H': case 'I': printf("4"); break;
      case 'J': case 'K': case 'L': printf("5"); break;
      case 'M': case 'N': case 'O': printf("6"); break;
      case 'P': case 'R': case 'S': printf("7"); break;
      case 'T': case 'U': case 'V': printf("8"); break;
      case 'W': case 'X': case 'Y': printf("9"); break;
      default: putchar(num);
    }

    return 0;

  }

}

The problem is that the getchar() is taking one value and changing that number/letter only when I want it to change the whole thing.

Things I have done: I found someone else code who did this already, copied it, changed it a bit (removed toupper function), stacked the cases side by side and it didn't work for some reason. Is it because of the placement of the switch statement? But I don't think it is because of that because it ends after printing one value.

What I want it to do:

Enter phone number: 1-800-COL-LECT
1-800-265-5328

What it does:

Enter phone number: 1-800-COL-LECT
1
Enter phone number: 5-469-COL-LECT
5

Answer 1

The problem in the code is that return 0; is inside of your while loop. What you need to do is move the return 0; outside of the loop and it will fix it.

#include <stdio.h>

main(){

  char num;

  printf("Please enter a phone number with letters to be converted into a phone number: \n");

  while ((num = getchar()) != '\n') {
    switch(num){
      case 'A': case 'B': case 'C': printf("2"); break;
      case 'D': case 'E': case 'F': printf("3"); break;
      case 'G': case 'H': case 'I': printf("4"); break;
      case 'J': case 'K': case 'L': printf("5"); break;
      case 'M': case 'N': case 'O': printf("6"); break;
      case 'P': case 'R': case 'S': printf("7"); break;
      case 'T': case 'U': case 'V': printf("8"); break;
      case 'W': case 'X': case 'Y': printf("9"); break;
      default: putchar(num);
    }
  }
  return 0;
}

Originally founded by @kaylum