Unable to understand result of this c program

Question

#include<stdio.h>
void main(){
  int i;
  i = 011;
  printf("%d",i);
}

This program gives output as 9. I don't know the reason for that. Please help me to figure out why this program is giving this output.

Do you know how to represent octal number in `C` ? – P0W Jan 04 '14 at 05:48 — P0W, Jan 04 '14 at 05:48
Octal constant literal `011` – BLUEPIXY Jan 04 '14 at 05:49 — BLUEPIXY, Jan 04 '14 at 05:49

score 7 · Answer 1 · answered Jan 04 '14 at 05:49

7

In C, you can represent the value 9 by:

answered Jan 04 '14 at 05:49

Bill Lynch

1

we can also use capital `X` for hex e.g. `0XFF` – Grijesh Chauhan Jan 04 '14 at 06:34

score 5 · Answer 2 · answered Jan 04 '14 at 05:49

5

In C/C++/Java, hex numbers begin with 0x. Octal numbers begin with 0.

011 is octal of 9

answered Jan 04 '14 at 05:49

P0W

And before you ask why, read [this](http://stackoverflow.com/q/1835465/1870232) – P0W Jan 04 '14 at 05:55

score 1 · Accepted Answer · answered Jan 04 '14 at 05:52

1

011 is octal number due to 0 preceding it

011 = 1*(8^1) + 1*(8^0)
    = 1*8 + 1*1
    = 8 +1
    = 9 in decimal(%d)

0x for hex and only digits(i.e 9) for decimal

answered Jan 04 '14 at 05:52

riteshtch

3 Answers3