Print a binary number in C

scvalex (Alexandru Scvortov) — Tue, 30 Oct 2007 11:53:18 GMT

These are two functions that print the binary representation of an integer. The first simply prints it out, while the second only prints out the relevant digits (i.e. cuts the first x 0 digits) in groups of four.

Explanation here.



#include 



/* Print n as a binary number */

void printbitssimple(int n) {

	unsigned int i;

	i = 1<<(sizeof(n) * 8 - 1);



	while (i > 0) {

		if (n & i)

			printf("1");

		else

			printf("0");

		i >>= 1;

	}

}



/* Print n as a binary number */

void printbits(int n) {

	unsigned int i, step;



	if (0 == n) { /* For simplicity's sake, I treat 0 as a special case*/

		printf("0000");

		return;

	}



	i = 1<<(sizeof(n) * 8 - 1);



	step = -1; /* Only print the relevant digits */

	step >>= 4; /* In groups of 4 */

	while (step >= n) {

		i >>= 4;

		step >>= 4;

	}



	/* At this point, i is the smallest power of two larger or equal to n */

	while (i > 0) {

		if (n & i)

			printf("1");

		else

			printf("0");

		i >>= 1;

	}

}



int main(int argc, char *argv[]) {

	int i;

	for (i = 0; i < 16; ++i) {

		printf("%d = ", i);

		printbitssimple(i);

		printf("\n");

	}



	return 0;

}

DZone Snippets: print a binary number code

Print a binary number in C