test_tty.c

#include <unistd.h>
#include <stdio.h>
#include <windows.h>

int main() {
  printf("isatty(fileno(stdout)) returned %d\n", isatty(fileno(stdout)));
  printf("_isatty(fileno(stdout)) returned %d\n", _isatty(fileno(stdout)));

  HANDLE h = GetStdHandle(STD_OUTPUT_HANDLE);

  if (h == INVALID_HANDLE_VALUE) {
    printf("GetStdHandle(STD_OUTPUT_HANDLE) failed.\n");
    return -2;
  }

  CONSOLE_SCREEN_BUFFER_INFO INFO;

  if ( !GetConsoleScreenBufferInfo(h, &INFO) ) {
    printf("GetConsoleScreenBufferInfo() failed.\n");
    return -1;
  }

  printf("cols=%d\n", (int)INFO.dwSize.X);

  return 0;
}