C Puzzles (gowrikumar.com)

One of these reminded me of my woeful attempts at IOCCC-like code, a Hello World implementation:

http://students.mimuw.edu.pl/~dj189395/nhp/czynic/programy/t...

Anyone else spot the uninitialized variable in the banner program?

Also:

> What's the output of the following program. (No, it's not 10!!!)

What's the point of including a program that calls malloc without including a prototype for it, after asking the reader earlier answer why such a program segfaults on IA-64 but not IA-32?

(The answer is: a constraint is violated, requiring a diagnostic, because an int * object pointer is assigned the return value of malloc whose implicit declaration marks it as returning int. The comment issue is a red herring.)

> Write a C program which prints Hello World! without using a semicolon

Here's one way, cheating a bit by abusing the definition of "a C program which prints":

    /tmp$ gcc hw.c
    hw.c:1:2: warning: #warning Hello world! [-Wcpp]
     #warning Hello world!

A more serious solution, though:

    /tmp$ cat hw.c
    #include <stdio.h>
    void main(void)
    {
        if (puts("Hello world!")) {}
    }
    /tmp$ gcc hw.c
    /tmp$ ./a.out
    Hello world!

    int main(int args, char *argv[printf("Hello, world!")]) { }

    int main(void) { /* ... */ }

    int main(int argc, char *argv[]) { /* ... */ }

I couldn't find the book at the hint provided... Could someone help me get that book. Thanks in advance

    #include <stdio.h>
    int main()
    {
     float a = 12.5;
     printf("%d\n", a);
     printf("%d\n", *(int *)&a);
     return 0;
    }

This program invokes undefined behaviour when it casts float\* to int\*, so technically it could print anything, or do something else. I'm not sure how using memcpy instead would impact the puzzle's point though.