整形数（int）转换成 二进制（字符串）形式

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


#define BUF_SIZE (100U)

int i_to_b(int a, char *str)
{
    
    
	int i = 0, j = 0;
	char tmp[BUF_SIZE];

	if (a == 0) {
    
    
		str[0] = '0';
		return 0;
	}
	while (a != 0) {
    
    
		tmp[i] = (a & 0x1) + '0';
		i++;
		a = a >> 1;
	}
	for (j = 0; j < i; j++) {
    
    
		str[j] = tmp[i - j - 1];
	}
	return 0;
}
int main(int argc, char ** argv)
{
    
    
	int a = 7;
	char str[BUF_SIZE] = {
    
     0 };
	i_to_b(a, str);
	fprintf(stdout, "%s\n", str);
	return 0;
}

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