Implement Stack Using Array with Push and Pop Operations

Code

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

#define MAX 10
typedef struct {
    int val[MAX];
    int top;
    int max;
} tpStackX;

enum {
    CMD_INVALID = 0,
    CMD_PUSH = 1,
    CMD_POP  = -1
};

tpStackX StackX = {.top = -1, .max=MAX-1};

int process_input(int *stack_val)
{
    char cmd[10];
    int val;
    *stack_val = 0;
// Try to read "push <num>"
    int res = scanf("%s", cmd);
    if (res != 1) {
        printf("Invalid input\n");
        return CMD_INVALID;
    }

    if (strcmp(cmd, "push") == 0) {
        if (scanf("%d", &val) == 1) {
            *stack_val = val;
            return CMD_PUSH;
        } else {
            printf("Invalid push command\n");
            return CMD_INVALID;
        }
    } else if (strcmp(cmd, "pop") == 0) {
        return CMD_POP;
    } else {
        printf("Unknown command: %s\n", cmd);
        return CMD_INVALID;
    }
}
void pop_stack()
{
    if(StackX.top >= 0){
        printf("%d\n",StackX.val[StackX.top]);
        StackX.top--;
    }
    else{
        printf("Stack Underflow\n");
    }
}
void push_stack(int val)
{
    if(StackX.top < StackX.max){
        StackX.top++;
        StackX.val[StackX.top] = val;
    }
    else{
        printf("Stack Overflow\n");
    }
}
void process_stack(int n) {
    // Your logic here
    int val = 0;
    int cmd = 0;
    while(n)
    {
        cmd = process_input(&val);
        if(cmd == 1){
            //push
            push_stack(val);
        }else if(cmd == -1){
             //pop
            pop_stack();
        }
        n--;
    }

}

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

    process_stack(n);
    return 0;
}

Solving Approach