Implement Stack Using Array with Push and Pop Operations

Code

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

#define MAX 10 // Maximum amount of numbers that stack can hold
#define EMPTY -1 // Defines the empty stack

typedef struct stack{
    int numbers[MAX]; // array of numbers.
    int top; // Index tracking.
}stack_t;

// Declare and initialize the global stack
stack_t stack_cli = {
    .numbers = {0}, // All numbers of the array to 0
    .top = -1 // Indexing pointer at -1
};

/**
 * Push operation to the stack.
 */
void push(stack_t *stack, int n) {
    if (stack->top == (MAX - 1)) {
        printf("Stack Overflow\n"); // Print overflow if stack is full.
    } else {
        stack->numbers[++stack->top] = n; // Push value into the stack.
    }
}

/**
 * Pop operation from the stack.
 */
void pop(stack_t *stack) {
    if (stack->top == EMPTY) {
        printf("Stack Underflow\n"); // Print underflow if stack is empty.
    } else {
        printf("%d\n", stack->numbers[stack->top]); // Pop and print the top value from the stack
        stack->top--;
    }
}

void process_stack(int n) {

    for (int i=0; i<n; i++) {
        char operation[20] = {0};
        int number;

        // Read the command from STDIN
        fgets(operation, sizeof(operation), stdin);

        if (strncmp(operation, "push", 4) == 0) { // Push operation
            // Extract the number that needs to be inserted to the stack.
            sscanf(operation + 5, "%d", &number);

            // Perform the operation
            push(&stack_cli, number);

        } else if (strncmp(operation, "pop", 3) == 0) { // Pop operation
            // Perform the operation
            pop(&stack_cli);
        } else {
            printf("Undefined command\n");
        }
    }
}

int main() {
    int n;
    scanf("%d", &n);
    getchar(); // Consume newline after number

    process_stack(n);
    return 0;
}

Solving Approach