Keith-S-Thompson

Demo for http://stackoverflow.com/q/16092520/827263

As you can see, g++ 4.7.2 reports the missing semicolon error in c.c, not in foo.h

Keith-S-Thompson

#include <stdio.h>
int main(void) {
    FILE *f;
}

Keith-S-Thompson

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Newsgroups: comp.lang.c
Date: Mon, 26 Aug 2013 09:19:57 -0700 (PDT)
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Keith-S-Thompson

#include <iostream>
using namespace std;

int agenext (int age);

int main ()
{
    int age = 42;
    cout << "age = " << age << "\n";
    agenext(age);

Keith-S-Thompson

/*
 * Test program based on code in the Wikipedia POSIX Threads
 * article, https://en.wikipedia.org/wiki/POSIX_Threads.
 *
 * Demo for http://stackoverflow.com/q/19128948/827263
 */
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

Keith-S-Thompson

korn.c is the "Best One Liner" winner of the 1987 International Obfuscated C Code Contest, by David Korn (yes, the author of the Korn Shell).

korn.hint, as the name implies, offers some hints.

A commenter on Stack Overflow asked for some clarification. I didn't want to post spoilers on the site, so I'm posting them here instead. If you haven't already (and if you're familiar with the rules of C) I encourage you to study the program for a while first.

=====

Here's the code:

Keith-S-Thompson

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Keith-S-Thompson

/*
 * In response to http://stackoverflow.com/a/22918463/827263 
 * "In C you can't declare variables/functions (in same scope) with the same name more than once."
 */

#include <stdio.h>

void yes_you_can(void);
void yes_you_can(void);
void yes_you_can(void);

Keith-S-Thompson

#include <stdio.h>
#include <stdint.h>
int main(void) {

    int64_t u = 0;
    int i;

    for(i=0;i<44;i++)
        u |= (uint64_t)1 << i;

Keith-S-Thompson

Demo for clang bug (demonstrated with version 3.4)
Based on this question on Stack Overflow.

===

It turns out that this isn't a bug; see Jens Gustedt's answer to the question.