Convert a decimal number into a binary number in C-Lang, including a handmade stack implement.

main.c

#include <stdio.h>

// Declare an array to emulate a stack
// Opacity of this stack is 10000
// `stack_index` is the cursor indicate current position
int stack[10000] = {0}, stack_index = 0;

// Functions define

void push(int x);

int pop();

int size();

void clear();

void decToBin(int x);

// End functions define

int main() {
    int decimal;
    scanf("%d", &decimal);
    decToBin(decimal);
    return 0;
}

// Push a number into stack
void push(int x) {
    stack[stack_index] = x;
    ++stack_index;
}

// Get the top element from the stack and remove it from the stack
int pop() {
    --stack_index;
    return stack[stack_index];
}

// Get the size of the stack
int size() {
    return stack_index;
}

// Clear the stack
void clear() {
    stack_index = 0;
}

// Convert a decimal number into a binary number
void decToBin(int x) {
    int decimal = x, remainder = 1;

    if (decimal == 0) {
        putchar('0');
    } else {
        // If decimal number is less than zero
        bool isNegative = x < 0;
        // If `decimal` less than zero, turn it to positive number
        decimal = decimal < 0 ? decimal * -1 : decimal;

        while (decimal != 0) {
            remainder = decimal % 2;
            decimal /= 2;
            push(remainder);
        }

        // If decimal number is less than zero, don't forget to print '-'
        if (isNegative) putchar('-');
        while (size() != 0) {
            printf("%d", pop());
        }
    }
    printf("\n");

    // Clear the stack for next input
    clear();
}