C++ int to binary

Question

I am using itoa builtin function, in order to convert an integer into binary and store it in char*. Every thing works fine and output is also correct (as expected). The only thing which goes wrong is that itoa doesn't work on open source like Linux, suse. Any suggestion for using itoa in open source environment.

Have you read: [how-to-output-an-int-in-binary](http://stackoverflow.com/questions/3269767/how-to-output-an-int-in-binary) — Martin York, Dec 29 '10 at 11:08
See http://stackoverflow.com/questions/228005/alternative-to-itoa-for-converting-integer-to-string-c — ismail, Dec 29 '10 at 11:12

score 5 · Accepted Answer · answered Dec 29 '10 at 11:09

To cite Wikipedia:

The itoa (integer to ASCII) function is a widespread non-standard extension to the standard C programming language. It cannot be portably used, as it is not defined in any of the C language standards; however, compilers often provide it through the header <stdlib.h> while in non-conforming mode, because it is a logical counterpart to the standard library function atoi.

In other words:

First check your compiler options, maybe you can force it to recognize this;
If that fails, either use one of the workarounds suggested by others, or just plain write it yourself. It's pretty trivial.

score 2 · Answer 2 · answered Dec 29 '10 at 11:16

2

use sprintf

int i = 100;

char str[5];

sprintf(str, "%d", i);

answered Dec 29 '10 at 11:16

Sudhakar Singh

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str should probably be around 12 characters long if it is to hold any sized integer. Also prefer snprintf to sprintf – doron Dec 29 '10 at 11:32

score 1 · Answer 3 · answered Dec 29 '10 at 11:07

1

itoa is non-standard function. You can get the behavior similar to itoa using stringstream

#include<sstream>
string a;
int i;
stringstream s;
s << i;
a = s.str();

answered Dec 29 '10 at 11:07

Senthil Kumaran

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`s < i`? I also don't believe that this converts to binary. – Puppy Dec 29 '10 at 11:08
sorry - `s < – Senthil Kumaran Dec 29 '10 at 11:10

score 1 · Answer 4 · answered Dec 29 '10 at 11:08

1

itoa isn't a standard C++ function. Use boost::lexical_cast, or use stringstreams

answered Dec 29 '10 at 11:08

Armen Tsirunyan

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C++ int to binary

4 Answers4