棧的實現（順序棧，C語言）
結構體聲明：
typedef struct {
ElemType *base; // 棧底元素指針
ElemType *top; // 棧頂指針
int stacksize; // 棧容量
int cnt; // 棧中元素數量
}SqStack;
其中棧底元素指針始終不變，棧頂指針指向棧頂元素的上方。
當base = top， cnt = 0；時，棧爲空棧。
當base = top = NULL;時，棧未初始化。
操作畫面：
下面放出代碼：
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#define STACKINITSIZE 100 // 儲存空間初始分配量
#define STACKINCREMENT 100 // 儲存空間分配增量
#define TRUE 1
#define FALSE 0
#define OK 1
#define ERROR -1
#define OVERFLOW -2
typedef int ElemType;
typedef int Status;
typedef struct {
ElemType *base; // 棧底指針
ElemType *top; // 棧頂指針
int stacksize; // 棧的容量
int cnt; // 棧當前元素個數
}SqStack;
/*
** 函數前向聲明
*/
SqStack *
InitStack();
Status
DestroyStack(SqStack *);
Status
ClearStack(SqStack *);
Status
StackEmpty(SqStack *);
int
StackLength(SqStack *);
Status
GetTop(SqStack *, ElemType *);
Status
AddStackSize(SqStack *);
Status
Push(SqStack *, ElemType);
Status
Pop(SqStack *, ElemType *);
Status
StackTraverse(const SqStack *);
/*
** 主函數，程序入口
*/
int main()
{
SqStack *sqs = InitStack();
ElemType e;
for (int i = 0; i < 110; i++) {
Push(sqs, i);
}
printf("目前棧長度：%d\n", StackLength(sqs));
printf("遍歷棧：\n");
StackTraverse(sqs);
Pop(sqs, &e);
printf("棧頂元素出棧：%d\n", e);
printf("目前棧長度：%d\n", StackLength(sqs));
DestroyStack(sqs);
system("pause");
return 0;
}
/*
** 函數定義
*/
SqStack *
InitStack() {
/*
構造一個空棧
*/
SqStack *sqs;
sqs = (SqStack *)malloc(sizeof(SqStack));
if (!sqs) exit(OVERFLOW);
sqs->base = (ElemType *)malloc(STACKINITSIZE * sizeof(ElemType));
if (!(sqs->base)) exit(OVERFLOW);
sqs->top = sqs->base;
sqs->stacksize = STACKINITSIZE;
sqs->cnt = 0;
return sqs;
}
Status
DestroyStack(SqStack *sqs) {
/*
銷燬棧，釋放資源
*/
assert(sqs != NULL);
free(sqs->base);
sqs->base = NULL;
sqs->top = NULL;
free(sqs);
sqs = NULL;
printf("棧已成功銷燬\n");
return OK;
}
Status
ClearStack(SqStack *sqs) {
assert(sqs != NULL);
sqs->top = sqs->base;
sqs->cnt = 0;
return OK;
}
Status
StackEmpty(SqStack *sqs) {
/*
若棧爲空棧，返回TRUE，否則返回FALSE
*/
assert(sqs != NULL);
if (sqs->cnt == 0)
return TRUE;
else
return FALSE;
}
int
StackLength(SqStack *sqs) {
/*
返回棧元素的個數，即棧的長度
*/
assert(sqs != NULL);
return sqs->cnt;
}
Status
GetTop(SqStack *sqs, ElemType *e) {
/*
若棧不空，用e返回棧頂元素，並返回OK；否則返回ERROR
*/
assert(sqs != NULL);
assert(e != NULL);
if (StackEmpty(sqs))
return ERROR;
*e = *(sqs->top - 1);
return OK;
}
Status
AddStackSize(SqStack *sqs) {
/*
增加棧的容量
*/
assert(sqs != NULL);
ElemType *add = (ElemType *)realloc(sqs->base,
(sqs->stacksize + STACKINCREMENT) * sizeof(ElemType));
if (!add) exit(OVERFLOW);
sqs->base = add;
sqs->stacksize += STACKINCREMENT;
printf("棧容量自動擴充\n");
return OK;
}
Status
Push(SqStack *sqs, ElemType e) {
/*
插入元素e爲新的棧頂元素
*/
assert(sqs != NULL);
if (sqs->cnt == sqs->stacksize)
AddStackSize(sqs);
*(sqs->top) = e;
(sqs->top)++;
(sqs->cnt)++;
return OK;
}
Status
Pop(SqStack *sqs, ElemType *e) {
/*
若棧不空，則刪除棧頂元素，用e返回其值
*/
assert(sqs != NULL);
if (StackEmpty(sqs))
return ERROR;
(sqs->top)--;
(sqs->cnt)--;
*e = *(sqs->top);
return OK;
}
Status
StackTraverse(const SqStack *sqs) {
/*
從棧底到棧頂依次遍歷棧
*/
assert(sqs != NULL);
ElemType *tmp = sqs->base;
for (; tmp != (sqs->top); tmp++) {
printf("%d\t", *tmp);
}
return OK;
}