การใช้ Linked List Implement Stack ในภาษา C

Stack ด้วย Linked List: กัน Overflow/Underflow ด้วย Dynamic Memory

โครงสร้างโหนด: struct node { int info; struct node *ptr; } มี pointer top ชี้โหนดบนสุด

Operations

• Push: สร้างโหนดใหม่ ชี้ ptr ไป top เดิม แล้ว top = โหนดใหม่
• Pop: ถอดโหนด top, top = top->ptr, free โหนดเก่า
• Display: วนจาก top ลงมา

โค้ด C สมบูรณ์ (พร้อมเมนู)

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

struct node {
    int info;
    struct node *ptr;
} *top, *top1, *temp;

int topelement();
void push(int data);
void pop();
void empty();
void display();
void destroy();
void stack_count();
void create();

int count = 0;

void main() {
    int no, ch, e;
    printf("\n 1 - Push");
    printf("\n 2 - Pop");
    printf("\n 3 - Top");
    printf("\n 4 - Empty");
    printf("\n 5 - Exit");
    printf("\n 6 - Display");
    printf("\n 7 - Stack Count");
    printf("\n 8 - Destroy stack");
    create();
    while (1) {
        printf("\n Enter choice : ");
        scanf("%d", &ch);
        switch (ch) {
            case 1: printf("Enter element : "); scanf("%d", &no); push(no); break;
            case 2: pop(); break;
            case 3: if (top == NULL) printf("stack is empty"); else { e = topelement(); printf("\n Top element : %d", e); } break;
            case 4: empty(); break;
            case 5: exit(0);
            case 6: display(); break;
            case 7: stack_count(); break;
            case 8: destroy(); break;
            default: printf(" wrong choice:Try again ");
        }
    }
}

void create() { top = NULL; }

void stack_count() { printf("\n no: of elements in stack : %d", count); }

void push(int data) {
    if (top == NULL) {
        top = (struct node *)malloc(1 * sizeof(struct node));
        top->ptr = NULL;
        top->info = data;
    } else {
        temp = (struct node *)malloc(1 * sizeof(struct node));
        temp->ptr = top;
        temp->info = data;
        top = temp;
    }
    count++;
}

void display() {
    top1 = top;
    if (top1 == NULL) { printf("empty stack"); return; }
    while (top1 != NULL) {
        printf("%d ", top1->info);
        top1 = top1->ptr;
    }
}

void pop() {
    top1 = top;
    if (top1 == NULL) { printf("\n error"); return; }
    top1 = top1->ptr;
    printf("\n Popped value : %d", top->info);
    free(top);
    top = top1;
    count--;
}

int topelement() { return(top->info); }

void empty() {
    if (top == NULL) printf("\n empty stack");
    else printf("\n stack not empty with %d values", count);
}

void destroy() {
    top1 = top;
    while (top1 != NULL) {
        top1 = top->ptr;
        free(top);
        top = top1;
        top1 = top1->ptr;
    }
    free(top1);
    top = NULL;
    printf("\n all are destroyed");
    count = 0;
}

ตัวอย่าง Output

1 - Push
2 - Pop
3 - Top
4 - Empty
5 - Exit
6 - Display
7 - Stack Count
8 - Destroy stack
Enter choice: 1
Enter element: 23
Enter choice: 1
Enter element: 45
Enter choice: 1
Enter element: 56
Enter choice: 2
Popped value: 56
Enter choice: 6
45 23
Enter choice: 8
all are destroyed
Enter choice: 6
empty stack
Enter choice: 5