栈的实现（动态数组）

栈的概念及结构

栈：一种特殊的线性表，其只允许在固定的一端进行插入和删除元素操作。进行数据插入和删除操作的一端。

称为栈顶，另一端称为栈底。栈中的数据元素遵守后进先出LIFO（Last In First Out）的原则。

压栈：栈的插入操作叫做进栈/压栈/入栈，入数据在栈顶。

出栈：栈的删除操作叫做出栈。出数据也在栈顶。

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栈的代码实现（动态数组实现）

栈的初始化

void StackInit(ST* ps)
{
    assert(ps);
    ps->a = NULL;
    ps->top = 0;
    ps->capacity = 0;
}

栈的销毁

void StackDestroy(ST* ps)
{
    assert(ps);
    free(ps->a);
    ps->a = NULL;
    ps->capacity = ps->top = 0;
}

栈的数据插入

void StackPush(ST* ps, STDataType x)
{
    assert(ps);
    if (ps->top == ps->capacity)
    {
        int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
        STDataType* tmp = realloc(ps->a, sizeof(STDataType) * newCapacity);
        if (tmp == NULL)
        {
            printf("realloc fail\n");
            exit(-1);
        }
        ps->a = tmp;
        ps->capacity = newCapacity;
    }
    ps->a[ps->top] = x;
    ps->top++;
}

栈的数据删除

void StackPop(ST* ps)
{
    assert(ps);
    assert(ps->top > 0);
    ps->top--;
}

取栈顶数据

STDataType StackTop(ST* ps)
{
    assert(ps);
    assert(!StackEmpty(ps));
    return ps->a[ps->top - 1];
}

栈中数据个数

int StackSize(ST* ps)
{
    assert(ps);
    return ps->top;
}

判断栈是否为空

bool StackEmpty(ST* ps)
{
    assert(ps);
    return ps->top == 0;
}

整体代码

Stack.h

#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <stdbool.h>


typedef int STDataType;
typedef struct Stack
{
    STDataType* a;
    int top;
    int capacity;
}ST;

void StackInit(ST* ps);
void StackDestroy(ST* ps);
void StackPush(ST* ps, STDataType x);
void StackPop(ST* ps);
STDataType StackTop(ST* ps);
int StackSize(ST* ps);
bool StackEmpty(ST* ps);

Stack.c

#include "Stack.h"

void StackInit(ST* ps)
{
    assert(ps);
    ps->a = NULL;
    ps->top = 0;
    ps->capacity = 0;
}

void StackDestroy(ST* ps)
{
    assert(ps);
    free(ps->a);
    ps->a = NULL;
    ps->capacity = ps->top = 0;
}

void StackPush(ST* ps, STDataType x)
{
    assert(ps);
    if (ps->top == ps->capacity)
    {
        int newCapacity = ps->capacity == 0 ? 4 : ps->capacity * 2;
        STDataType* tmp = realloc(ps->a, sizeof(STDataType) * newCapacity);
        if (tmp == NULL)
        {
            printf("realloc fail\n");
            exit(-1);
        }
        ps->a = tmp;
        ps->capacity = newCapacity;
    }
    ps->a[ps->top] = x;
    ps->top++;
}

void StackPop(ST* ps)
{
    assert(ps);
    assert(ps->top > 0);
    ps->top--;
}

STDataType StackTop(ST* ps)
{
    assert(ps);
    assert(!StackEmpty(ps));
    return ps->a[ps->top - 1];
}

int StackSize(ST* ps)
{
    assert(ps);
    return ps->top;
}

bool StackEmpty(ST* ps)
{
    assert(ps);
    return ps->top == 0;
}

test.c

#include "Stack.h"

void TestStack()
{
    ST st;
    StackInit(&st);

    StackPush(&st, 1);
    StackPush(&st, 2);
    StackPush(&st, 3);
    StackPush(&st, 4);
    
    while (!StackEmpty(&st))
    {
        printf("%d ", StackTop(&st));
        StackPop(&st);
    }

    StackDestroy(&st);
}


int main()
{
    TestStack();
    return 0;
}