栈的实现

复习使用C语言实现栈

PS：其中有一个动态增加内存的方法，要注意

#define STACK_INIT_SIZE 100
#define STACKINCREMENT 100

typedef struct{
    SElemType *base;
    SElemType *top;
}SqStack;

status InitStact(SqStack %S){
    S.base = (SElemType *)malloc(STACK_INIT_SIZE * sizeof(SElemType));
    if(!S.base)
        exit(OVERFLOW);
    S.top = S.base;
    S.stacksize = STACK_INIT_SIZE;
    return OK;
}

status GetTop(SqStack S,SElemType &e){  //top元素保存在e中
    if(S.top == S.base)
        return ERROR;
    e = *(S.top-1);
    return OK;
}

status Push(SqStack &S,SElemType e){
    if(S.top - S.base >= S.stacksize){  //栈已满
        //动态增加内存
        S.base = (SElemType *)realloc(S.base,(S.stacksize+STACKINCREMENT)*sizeof(SElemType));
        if(!S.base)
            exit(OVERFLOW);
        S.top = S.base + S.stacksize;
        S.stacksize + = STACKINCREMENT;
    }
    *S.top++ = e;
    return OK;
}

status Pop(SqStack &S,SElemType &e){
    if(S.top == S.base)
        return ERROR;
    e = * --S.top;
    return Ok;
}