数据结构复习之顺序栈的实现

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

//常量定义
#define TRUE 1
#define FALSE 0
#define OK 1
#define ERROR 0
#define INFEASIBLE -1
#define OVERFLOW -2

//自定义类型
typedef int Status; //函数返回值类型为int
typedef int ElemType; //栈元素类型为int

//栈的存储结构定义
typedef struct {
    ElemType *elem;
    int top;
    int size;
    int increment;
} SqStack;


//栈的初始化函数
Status init(SqStack &S, int size, int inc) {
    //分配存储空间
    S.elem = (ElemType*)malloc(size * sizeof(ElemType));

    //分配失败
    if(S.elem == NULL) {
        return OVERFLOW;
    }

    S.top = 0; //设置栈顶为0，因为当前是空栈
    S.size = size; //栈的长度
    S.increment = inc; //每次增加的长度
    return OK;
}

//入栈函数
Status push(SqStack &S, ElemType e) {

    //如果栈已经满了,则开辟新的空间
    ElemType *newbase;
    if(S.top >= S.size) {

        newbase = (ElemType*)realloc(S.elem, (S.size + S.increment) * sizeof(ElemType));

        if(newbase == NULL) {
            return OVERFLOW;
        }

        S.elem = newbase;
        S.size = S.size + S.increment;
    }

    //将e赋值给S.elem[top]，并且是top加1
    S.elem[S.top++] = e;
    return OK;
}

//出栈函数
Status pop(SqStack &S,ElemType &e) {
    if(S.top == 0) {
        return ERROR;
    }
    S.top--;
    e = S.elem[S.top];
    return OK;
}

//取栈顶元素
Status getTop(SqStack &S, ElemType &e) {
    if(S.top == 0) {
        return ERROR;
    }

    e = S.elem[S.top-1];
}

//清空栈
Status clear(SqStack &S) {
    int i;
    ElemType e;
    for(i = S.top; i > 0; i--) {
        pop(S, e);
        printf("%d\n", e);
    }
}

//判断栈是否为空
Status isEmpty(SqStack &S) {    
    return (S.top == 0 ? TRUE : FALSE);
}

int main() {

    //声明一个栈类型的变量stack
    SqStack stack;

    //声明一个栈元素类型的变量e
    ElemType e;

    //初始化栈
    init(stack, 5, 1); //初始化栈

    //判空
    printf("%s\n", isEmpty(stack) == 1 ? "stack is empty" : "stack isn't empty");

    //入栈
    push(stack, 1);
    push(stack, 2);

    //判空
    printf("%s\n", isEmpty(stack) == 1 ? "stack is empty" : "stack isn't empty");

    //取栈顶元素
    getTop(stack, e);
    printf("%d\n", e); //2

    //出栈
    pop(stack, e);
    printf("%d\n", e); //2

    //清空栈
    clear(stack);

    //判空
    printf("%s\n", isEmpty(stack) == 1 ? "stack is empty" : "stack isn't empty");
}