栈的简单实现

一、头文件、宏及函数声明：

#include <stdio.h>
#include <stdlib.h>
#define MAX 100

typedef enum status {
    success, overflow, underflow, fatal
} Status;

typedef int StackEntry;

typedef struct stack {
    int top;
    StackEntry* entry;
    int stack_size;
} Stack, *StackPtr;

Status Stack_push(StackPtr s, StackEntry item);
Status Stack_Pop(StackPtr s, StackEntry* item);
Status Stack_Top(StackPtr s, StackEntry* item);

 

二、函数实现：

Status Stack_push(StackPtr s, StackEntry item) {
    Status outcome = success;
    if(s->top == MAX-1) {
        outcome = overflow;
    } else {
        s->top++;
        s->entry[s->top] = item;
    }
    return outcome;
}

Status Stack_Pop(StackPtr s, StackEntry* item) {
    Status outcome = success;
    if(s->top == -1) {
        outcome = underflow;
    } else {
        *item = s->entry[s->top--];
    }
    return outcome;
}

Status Stack_Top(StackPtr s, StackEntry* item) {
    Status outcome = success;
    if(s->top == -1) {
        outcome = underflow;
    } else {
        *item = s->entry[s->top];
    }
    return outcome;
}