Find the output of?

Question

It is a question given in one of our placement Exams. explain the output of the following code...

#include <stdio.h>

int main(void)
{
   int i = 320;
   char *ptr = (char *)&i;
   printf("%d", *ptr);
   return 0;
}

@Hari Krishna Singireddi It is interesting what is the "placement Exams"? — Vlad from Moscow, Aug 08 '15 at 17:48
@LeFou the question is, find the output of the given code... — Hari Krishna Singireddi, Aug 08 '15 at 17:51
@Hari: The output _when_? On what system? On what day of the week? The program does not have well-defined standard-mandated semantics. — Lightness Races in Orbit, Aug 08 '15 at 17:53
@Lightness Races in Orbit, Yes, It's definitely a stupid exam this was the only information given to us.... — Hari Krishna Singireddi, Aug 08 '15 at 17:56

Lightness Races in Orbit · Answer 1 · 2019-06-29T19:57:38.020

6

You will get the numeric value of the "first" byte that makes up the int with value 320.

The precise output depends on the endianness of your platform:

Here are the octet-components of a 32-bit int on a little-endian, two's-complement system:

(An octet is an 8-bit byte. Your platform probably has octets as char, however more exotic platforms, with larger CHAR_BIT values, do exist.)

edited Jun 29 '19 at 19:57

answered Aug 08 '15 at 17:49

Or if sizeof int is 1 then the value of first char is 320... – Antti Haapala -- Слава Україні Jun 29 '19 at 04:16
@AnttiHaapala https://stackoverflow.com/q/50930891/560648 – Lightness Races in Orbit Jun 29 '19 at 11:35
`CHAR_BIT != 8` – Antti Haapala -- Слава Україні Jun 29 '19 at 12:16
@AnttiHaapala Yes, it's possible (e.g. on Crays `sizeof(int)` was 1) – Lightness Races in Orbit Jun 29 '19 at 19:55

1 Answers1