CODEWITHSUNDEEP
c
Pratul Singhal
Pratul Singhal

Reputation: 23

Problem understanding output of C program

I have the following program:

#include<stdio.h>
int main()
{
int i =257;
int *iptr =&i;
printf("%d%d",*((char*)iptr),*((char*)iptr+1));
return 0; 
}

The output is:

1 1

I am not able to understand why the second value is 1. Please explain.

Upvotes: 2

Views: 146

Answers (3)

Henno Brandsma
Henno Brandsma

Reputation: 2166

257 hexadecimally as 4 bytes = 0x00000101, which on Intel machines is stored in memory as 01 01 00 00. iptr points to the first 01, and iptr+1 to the second.

Upvotes: 2

peoro
peoro

Reputation: 26060

Because 257 in binary is 00000001 00000001: So both the first and the second bytes representing it are set to 1.

(char*)iptr is the char (thus 1 byte) pointed by iptr, and (char*)iptr+1 is the next byte.

Upvotes: 5

Steve Jessop
Steve Jessop

Reputation: 279215

Same reason the first value is coming out 1. You're accessing a single byte at a time from an int. Since 257 is 0x0101, the two least significant bytes each contain the value 1.

Probably your int is 4 bytes long and stored little-endian, although I suppose it could be 2 bytes long with either endian-ness.

Upvotes: 6

Related Questions