[数据结构与算法] : 栈的链式实现

头文件

typedef int ElementType;

#ifndef _STACKLI_H_
#define _STACKLI_H_

struct Node;
typedef Node *PtrToNode;
typedef PtrToNode Stack;

int IsEmpty(Stack S);
Stack CreateStack(void);
void DisposeStack(Stack S);
void MakeEmpty(Stack S);
void Push(ElementType X, Stack S);
ElementType Top(Stack S);
void Pop(Stack S);

#endif

源文件

#include "stackli.h"
#include <malloc.h>
#include <stdlib.h>

struct Node
{
    ElementType Element;
    PtrToNode Next;
};

int IsEmpty(Stack S)
{
    return S->Next == NULL;
}

// 创建栈的头节点
Stack CreateStack(void)
{
    Stack S = (Stack)malloc( sizeof(struct Node) );
    if( S == NULL )
    {
        fprintf(stderr, "%s
", "Out of space!!!");
        exit(-1);
    }
    S->Next = NULL;
    return S;
}

// 销毁栈(包括头节点)
void DisposeStack(Stack S)
{
    MakeEmpty(S);
    free(S);
}

// 清空栈就是弹出所有数据
void MakeEmpty(Stack S)
{
    if(S == NULL)
    {
        fprintf(stderr, "%s
", "Must use CreateStack first");
        exit(-1);
    }
    else
        while( !IsEmpty(S) )
            Pop(S);
}

// 进栈, 插入到头节点之后
void Push(ElementType X, Stack S)
{
    PtrToNode TmpCell = (PtrToNode)malloc( sizeof(struct Node) );
    if(TmpCell == NULL)
    {
        fprintf(stderr, "%s
", "Out of space!!!");
        exit(-1);
    }
    else
    {
        TmpCell->Element = X;
        TmpCell->Next = S->Next;
        S->Next = TmpCell;
    }
}

// 返回栈顶元素, 注意S不能为空
ElementType Top(Stack S)
{
    if( IsEmpty(S) )
    {
        fprintf(stderr, "%s
", "Empty stack");
        return -1;
    }
    else
        return S->Next->Element;
}

// 出栈, 删除头节点的后继
void Pop(Stack S)
{
    if( IsEmpty(S) )
    {
        fprintf(stderr, "%s
", "Empty stack");
    }
    else
    {
        PtrToNode P = S->Next;
        S->Next = P->Next;
        free(P);
    }
}

测试文件

#include <stdio.h>
#include "stackli.h"

main( )
{
    Stack S;
    int i;

    S = CreateStack( );
    for( i = 0; i < 10; i++ )
        Push( i, S );

    while( !IsEmpty( S ) )
    {
        printf( "%d ", Top( S ) );
        Pop( S );
    }

    DisposeStack( S );
    return 0;
}