Question

Possible Duplicate:
Accessing arrays by index[array] in C and C++

#include <stdio.h>
int main()
{       
    int a=3, b = 5;
    printf(&a["Ya!Hello! how is this? %s\n"], &b["junk/super"]);
    printf(&a["WHAT%c%c%c  %c%c  %c !\n"], 1["this"],
    2["beauty"],0["tool"],0["is"],3["sensitive"],4["CCCCCC"]);

    return 0;
}

This is one of the practice problems that I was given in class. I’m trying to figure out how this code was able to get to the output, which is

Hello! how is this? super
That is C !

The &a[” %s”] operation. How does that work? along with the seco

Answer 1

The code

&a["Ya!Hello! how is this? %s\n"]

Is interpreted as

&(a["Ya!Hello! how is this? %s\n"])

Since all C-style strings are pointers, this is a bizarre but legal usage of the fact that

arr[i]

and

i[arr]

are both legal in C. Consequently, the code should be interpreted as

&("Ya!Hello! how is this? %s\n"[a])

And since a = 3, this is the character H. Since we take the address of this character, this gives a pointer to the C-style string

"Hello! how is this? %s\n"

Using this as a starting point, you can try to decode the rest of the program.

Hope this helps!