dec to binary

dec2bin.c

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

// function reverse string instead of strrev (strrev not exist in linux)
char *rev_string(char *str)
{
    int start = 0;
    int end = strlen(str) - 1;
    char tmp;

    if (!str || !*str)
    {
        exit(0);
    }

    while(start < end)
    {
        tmp = *(str + start);
        *(str + start) = *(str + end);
        *(str + end) = tmp;

        start++;
        end--;
    }
    return str;
}
// function covert decimal to binary (to string -> reverse string)
char *dec2bin(int n)
{
    char *str = (char *)malloc(100 * sizeof(char));
    int i = 0;
    while(n > 0)
    {
        if(n % 2 == 0)
        {
            *(str + i) = '0';
        }
        else
        {
            *(str + i) = '1';
        }
        i++;
        n = n / 2;
    }
    return rev_string(str);
}

int main(int argc, char const *argv[])
{
    int number;
    char *binary = (char *)malloc(100 * sizeof(char));

    printf("Number: ");
    scanf("%d", &number);

    binary = dec2bin(number);

    printf("Ket qua: ");
    puts(binary);

    return 0;
}