Character entry causing infinite loop in C

Question

Ok, so I've searched several places for an answer to this, and I found the answer to the same problem in C++, but it involved clearing cin and that stuff, and I'm not sure how to translate that to C. I apologize in advance if this was, in fact, answered somewhere else, and I just missed it. Also, keep in mind that I'm basically teaching myself C, and I don't know much beyond what you see in this code.

Basically, my problem is this: I am running a loop that asks for input and then uses a switch statement to choose what happens. The switch takes an int, and it works fine with any numerical entry. When you enter a char, however, it just loops infinitely, giving no chance to input anything else.

Assuming this is the same problem as it was in the C++ examples I looked up - and I'm not 100% sure it is - when I enter a char it gets added to the buffer, and never gets cleared, so each time it loops the invalid input gets used again. Clearing the buffer seemed simple enough in C++, but I was unable to find anything I could understand in C.

Here's my code, for reference:

int main()
{


  while(1)
  {
    printf("(1-10) -> Run a program | (-1) -> Display menu | (0) -> Quit : ");

    int quit = 0;
    int select;
    scanf("%d", &select);
    switch(select)
    {
      case 1:
        printf("%s", pgmRun);
        helloWorld();
        printf("%s", pgmEnd);
        break;

      //More cases here

      case 0:
        quit = 1;
        break;
      default:
        printf("\n");
        printf("Error: Invalid input\n");
        printf("\n");
    }

    if(quit == 1)
      break;
  }
return 0;
}

Thanks in advance for your help, and sorry for such a lengthy post. I tend to be long-winded. :P

Answer 1

fflush(stdin) has undefined behavior. If you want to discard characters entered after the scanf() call, you can read and discard them.
You can use getchar() to clear the character.