Question

I am developing a simple compiler in the cygwin environment using flex and bison generating C code as output and I have generated a sequence of code intended to read two integers followed by a char.

Whereas I thought I knew basic c code I am suffering a problem with the code below where I input two integers, but it never asks for the character after reading the integers!

What is the best way to handle generating code like this, should I always clear the character buffer before performing a scan or a getchar() or have i just made a mistake somewhere!!!

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

int main(int argc, char **argv) {

   int a = 0;
   int b = 0;
   char f = '\0';

   scanf("%d",&a);

   scanf("%d",&b);

   f = getchar();
   fflush( stdin );

   return EXIT_SUCCESS;

}

Answer 1

If you want to read each part of the input on a new line, change your scanf format string so that it consumes the '\n', since at the moment f = '\n'. ie. use "%d\n" instead of "%d".

And then you can print the values to make sure (printf("a: %d, b: %d, f: %c\n", a, b, f);)

$ ./test
2
4
b
a: 2, b: 4, f: b

An alternative is also to replace the two scanf statements and the getchar with a single scanf statement: scanf("%d\n%d\n%c", &a, &b, &f);.