Convert decimal to binary using bitwise operations. [Supports showing the memory of floats as well]

dec2bin.c

#include<stdio.h>
#include<string.h>

/*
 * bitwisei -- decimal to binary using bitwise operators
 * 			masks n with 0001
 * 			then with 0010
 * 			then with 0100
 * 			then with 100
 * 			in order to find out if the corresponding bit is on in n
 * n: number int decimal
 * buf: buffer for output, must be able to contain
 * 		sizeof(n)*8 char + '\0'
 */
int bitwisei(int n, char* buf){
	int i, ri;

	ri=sizeof(n)*8;
	buf[ri--] = '\0';

	for(i=0; i < sizeof(n) * 8; i++)
		buf[ri--] = (n & 1<<i)?'1':'0';

	return 0;
}

/*
 * same as above, just for floats
 */
int bitwisef(float f, char* buf){
	int n;

	if (sizeof(f) != sizeof(int)){
		buf[0]='\0';
		return -1;
	}
	memcpy(&n, &f, sizeof(f));

	return bitwisei(n, buf);
}

int main(){
	float f;
	char opt;
	char buf[100];

	scanf("%f%c", &f, &opt);

	if (opt == 'i' || opt == '\n')
		bitwisei(f, buf);
	else if(opt == 'f')
		bitwisef(f, buf);


	puts(buf);
}