How to extract bits from an integer in C?

Question

So i'm trying to extracts bits from a 32=bit binary integer using bit shifting and masking, but i'm sightly off by one.

#include <stdio.h> int main (){ int number = 87; //0000 000 0000 0000 0000 0000 0101 0111 int i; int bit; int g = 0; for(i = 32; i > 0; i--){ if(g%4==0 && g!=0){ printf(" "); } g++; bit = (number >> i) & 1; printf("%d", bit); } printf("\n"); return 0; }

Have you tried stepping through the code line by line in a debugger? — Some programmer dude
– Some programmer dude, Commented Jan 26, 2017 at 5:24
Also, remember that bit numbers are zero-based. The first bit is number 0, the last bit in a 32-bit number is number 31. — Some programmer dude
– Some programmer dude, Commented Jan 26, 2017 at 5:25
ahhh, nevermind. Stupid for loop was throwing me off. Thanks for the hints — christian
– christian, Commented Jan 26, 2017 at 5:28

zx485 · Accepted Answer · 2017-01-26 08:26:35Z

1

There is logic missing in your code..

Use

for(i **= 31**; i **>=** 0; i--)

instead of

for(i **= 32**; i **>** 0; i--)

Comment if it works for you

edited Jan 26, 2017 at 8:26

zx485

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answered Jan 26, 2017 at 5:32

ntshetty

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