C :: Convert Decimal To Binary On Language

The goal of my program is to convert a decmial number to a binary number.First, the program gets an input to an array of chars, and the function translate_dec_bin converts this array to a decimal number through the strtoul function.The problem is that my program prints the binary number with an additional "0".For exmaple, for the input 1 - the program prints 01 instead of 1, for the input 3 - the program prints 011 instead of 11.

Code:

#include <stdio.h>
#include <stdlib.h>
#define MAX_LEN 20
void translate_dec_bin(char s[]){
char st[sizeof(unsigned)*20] = { 0 };
}

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