Question

I am working on implementing a brainfuck interpreter, and I’m struggling with the call of two consecutive , commands.

Here’s an extract of my code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MEM_SIZE 30000
#define MAX_LINE_LENGTH 256

int main (int argc, char **argv)
{
    char *input = ",.,.";
    char bytes [MEM_SIZE] = {0};

    int pos=0;
    int i=0;

    while (input[i] != '\0'){

        switch (input[i]){
            case '.':
                printf ("%c", bytes[pos]);
                break;
            case ',':
                printf ("Enter Number:\n");
                bytes[pos] = fgetc (stdin);
                printf ("Number Entered\n");
                break;
            default:
                break;
        }
        i++;
    }
    return EXIT_SUCCESS;
}

The output of the program is the following:

Enter Number:
3                  // This is me, manually entering the value.
Number Entered
3Enter Number:
Number Entered

Why isn’t the second call to fgetc working?

Answer 1

What makes you think the second call to fgetc isn’t working ? The second fgetc reads in an \n (you did press return, right?).

Another problem, you are reading into a char. fgetc returns an int. You should check this for EOF before blindly using it.