Binary number conversion in c language

Question

Possible Duplicate:
Is there a printf converter to print in binary format?

Is there any built in function to convert a decimal number to binary number? Is there any format specifier for binary numbers? For hex it is %x and for binary?

You have to do this manually. – Ramy Al Zuhouri Dec 12 '12 at 02:51 — Ramy Al Zuhouri, Dec 12 '12 at 02:51

score 2 · Answer 1 · answered Dec 12 '12 at 02:31

2

No, C does not have binary conversion functions built in. However, they're not hard to write and are a good exercise to demonstrate your understanding of binary arithmetic.

answered Dec 12 '12 at 02:31

Greg Hewgill

951,095
183
1,149
1,285

Well `strtoul( , ,2)` reads binary strings just fine, which is one part of the problem. – dmckee --- ex-moderator kitten Dec 12 '12 at 02:37
@Cornstalks That would be why the above is a comment to Greg's *"C does not have binary conversion functions built in"* and not an answer. – dmckee --- ex-moderator kitten Dec 12 '12 at 03:03

score -1 · Answer 2 · answered Dec 12 '12 at 03:12

-1

some libc have it as extension (you can printf a %b ) but here is a basic macro implementation if you just need the string representation of the binary

#define putbin(d) do{ \ 
  unsigned long long i=1ULL<<63; \ 
  while (!((unsigned long long) d & (i/=2))); /* optional - remove leading zeroes */ \ 
    do { ( (unsigned long long) d & i) ? write(1,"1",1) : write(1,"0",1); } \
    while (i/=2); \ 
write(1,"\n",1); /* optional - add new line */ \ 
} while (0)

answered Dec 12 '12 at 03:12

technosaurus

7,676
1
30
52

btw, oddly it was dietlibc that had %b option in printf – technosaurus Dec 12 '12 at 03:15
1

This code fails (with an infinite loop) for a pretty common use case. – Greg Hewgill Dec 12 '12 at 03:38

Binary number conversion in c language

2 Answers2