C实现链表形式的栈

一、头文件、宏及函数声明：

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

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

typedef int StackEntry;

typedef struct stacknode {
    StackEntry entry;
    struct stacknode* next;
} StackNode, *StackNodePtr;

typedef struct stack {
    StackNodePtr top;
} Stack, *StackPtr;

Status Stack_Push(StackPtr s, StackEntry item);
Status Stack_Pop(StackPtr s, StackEntry* item);
StackNodePtr MakeNode(StackEntry item);
StackEntry Stack_Top(StackPtr s, StackEntry* item);
int Stack_Empty(StackPtr s);

 

二、函数实现：

Status Stack_Push(StackPtr s, StackEntry item) {
    Status outcome = success;
    StackNodePtr np = MakeNode(item);
    if(np == NULL) {
        outcome = overflow;
    } else {
        np->next = s->top;
        s->top = np;
    }

    return outcome;
}

StackNodePtr MakeNode(StackEntry item) {
    StackNodePtr np = (StackNodePtr)malloc(sizeof(StackNode));
    np->entry = item;
    np->next = NULL;
    return np;
}

Status Stack_Pop(StackPtr s, StackEntry* item) {
    Status outcome = success;
    if(Stack_Empty(s)) {
        outcome = underflow;
    } else {
        StackNodePtr temp = s->top;
        s->top = temp->next;
        *item = temp->entry;
        free(temp);
    }
    return outcome;
}

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

int Stack_Empty(StackPtr s) {
    if(s->top == NULL) 
        return 1;
    else 
        return 0;
}

 

三、测试函数：

int main(int argc, char const *argv[]) {
    Status s;
    StackPtr sp = (StackPtr)malloc(sizeof(StackPtr));
    s = Stack_Push(sp, 100);
    if(s == success) {
        StackEntry* item = malloc(sizeof(StackEntry)*10);
        s = Stack_Top(sp, item);
        if(s == success) {
            printf("%d\n", sp->top->entry);
        }
        free(item);
    }
    free(sp);
    return 0;
}