顺序栈

#include<iostream>
using namespace std;
#define STACKLENGTH 20
typedef struct Stack
{
    int s[STACKLENGTH];
    int t;
}Stack;

void initial(Stack *stack)
{
    //第一个元素舍去不用
    stack->s[0] = 0;
    stack->t = 0;
}
//入栈
bool push(Stack *stack,int elem)
{
    if (stack->t+1 == STACKLENGTH)
    {
        cout<<"overflow"<<endl;
        return false;
    }

    stack->t++;
    stack->s[stack->t] = elem;
    return true;
}
//弹出栈元素
bool pop(Stack *stack ,int *elem)
{
    if (stack->t <= 0 )
    {
        cout<<"栈空！"<<endl;
        return false;
    }
    *elem = stack->s[stack->t];
    stack->t--;
    return true;
}
//读取栈顶元素
bool top(Stack *stack, int *elem)
{
    if (stack->t <= 0 )
    {
        cout<<"栈空!"<<endl;
        return false;
    }
    *elem = stack->s[stack->t];

    return true;
}

//判断栈是否为空
bool isempty(Stack stack)
{
    return !stack.t;
}

//取出栈顶元素
bool poptop(Stack *stack ,int *elem)
{
    if(top(stack,elem) && pop(stack,elem))
    {
        return true;
    }
    return false;

}
void print(Stack stack)
{
    int nlength = stack.t;
    for (int i = 1 ; i <= nlength;i++ )
    {
        cout<<stack.s[i]<<endl;
    }
}
int main()
{
    Stack stack;
    initial(&stack);
    push(&stack,1);
    push(&stack,2);
    print(stack);
    cout<<"---------------------------"<<endl;
    int ele;
    if(pop(&stack,&ele))
    {
        cout<<ele<<endl;
    }
    //print(stack);
    cout<<"-----------------------------"<<endl;
    if (top(&stack,&ele))
    {
        cout<<ele<<endl;
    }
    cout<<"---------------------------------"<<endl;
    if (!isempty(stack))
    {
        cout<<"栈非空!"<<endl;
    }

    cout<<"-------------------------------------"<<endl;
    if (poptop(&stack,&ele))
    {
        cout<<ele<<endl;
    }

    cout<<"------------------------------------"<<endl;
    if (isempty(stack))
    {
        cout<<"栈空!"<<endl;
    }
    return 0 ;
}

t不仅标志栈是否为空，还是数组的下标，两个作用！