Decimal to Binary in C

// decimal_2_binary.c

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

char* decimal2binary(unsigned);

int main(void){


    unsigned n = 10;
    printf("Enter a Positive Number? ");
    scanf("%u", &n);
    
    char *binary = decimal2binary(n);

    int i;
    for (i=0; i<32; i++)
        printf("%i", binary[i]); 

    printf("\n");
    return 0;
}


char* decimal2binary(unsigned x){
    int size = sizeof(unsigned*)* CHAR_BIT;
    char *bits = (char*) malloc(size);
    char *ptr = bits;
    
    ptr +=(size-1);
    while (x > 0){
        char t;
        t = x &1;
        x = x >>1;
        *ptr--=t;
    }
    while ( ptr - bits >= 0){
        *ptr--=0;
    }

    return bits;
}