链队(POP出了些问题)

[weixin_40458321]

#include "stdio.h"
#include "stdlib.h"
#define OK 1
#define ERROR 0

int n=0;

typedef int ElemType;
typedef struct linknode
{
ElemType data;
struct linknode *next;
}linknode;

typedef struct Queue
{
linknode *front;
linknode *rear;
}linkqueue;

int initial(linkqueue *Q)
{
linknode *p;
p=(linknode *)malloc(sizeof(linknode));
if(!p)
{
exit(1);
return ERROR;
}
p->next=NULL;
Q->front=Q->rear=p;
return OK;
}

int Empty(linkqueue *Q)
{
return(Q->front==Q->rear?OK:ERROR);
}

int push(linkqueue *Q)
{
linknode *p;
p=(linknode *)malloc(sizeof(linknode));
if(!p)
{
exit(1);
return ERROR;
}
printf("请输入进队整数：");
scanf("%d",&p->data);
Q->rear->next=p;
Q->rear=p;
n++;
return OK;
}

int pop(linkqueue *Q)
{
linknode *p;
if(Q->front==Q->rear)
return ERROR;
else
{
p=Q->front->next;
if(Q->front->next=Q->rear)
{
Q->front->next=NULL;
Q->rear=Q->front;
}
else
{
Q->front->next=p->next;
}
free(p);
n--;
return OK;
}
}

int gettop(linkqueue *Q)
{
linknode *p;
if(Q->front==Q->rear)
return ERROR;
else
{
p=Q->front->next;
}
return p->data;
}

void print(linkqueue *Q)
{
int i=0;
linknode *p;
if(Empty(Q))
printf("队为空！");
else
{
printf("队内元素为：");
for(p=Q->front->next;i<n;i++,p=p->next)
{
printf("%d ",p->data);
}
printf("\n队内元素个数为%d个",n);

}
}




int main(void)
{
linkqueue q;
linkqueue *Q;
Q=&q;
int i,e;
printf("1.链队初始化\n2.链队判空\n3.进队\n4.出队\n5.队顶\n6.遍历队\n7.退出\n\n\n");
while(scanf("%d",&i)!=EOF)
{
switch(i)
{
case 1:if(initial(Q))printf("初始化成功！");break;
case 2:if(Empty(Q))printf("队空！");
else printf("队未空！");
break;
case 3:if(push(Q))printf("进队成功！");break;
case 4:if(pop(Q))printf("出队成功！");
else printf("队为空！");
break;
case 5:if(!gettop(Q))printf("队为空");
else
{
e=gettop(Q);
printf("队顶元素为%d",e);
}
break;
case 6: print(Q);break;
case 7: exit(0);
}
putchar(10);
}
}

[自信男孩]

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

#define OK 1
#define ERROR 0

int n=0;

typedef int ElemType;

typedef struct linknode
{
    ElemType data;
    struct linknode *next;
}linknode;

typedef struct Queue
{
    linknode *front;
    linknode *rear;
}linkqueue;

int initial(linkqueue *Q)
{
    linknode *p;
    p = (linknode *)malloc(sizeof(linknode));
    if(!p)
    {
        exit(1);
        return ERROR;
    }
    p->next = NULL;
    Q->front = Q->rear = p;
    return OK;
}

int Empty(linkqueue *Q)
{
    return(Q->front == Q->rear?OK:ERROR);
}

int push(linkqueue *Q)
{
    linknode *p;
    p = (linknode *)malloc(sizeof(linknode));
    if (!p) {
        exit(1);
        return ERROR;
    }
    printf("请输入进队整数：");
    scanf("%d",&p->data);
    Q->rear->next = p;
    Q->rear = p;
    n++;
    return OK;
}

int pop(linkqueue *Q)
{
    linknode *p;
    if(Q->front == Q->rear)
        return ERROR;
    else
    {
        p = Q->front->next;
        if(Q->front->next == Q->rear)
        {
            Q->front->next = NULL;
            Q->rear = Q->front;
        }
        else
        {
            Q->front->next = p->next;
        }
        free(p);
        n--;
        return OK;
    }
}

int gettop(linkqueue *Q)
{
    linknode *p;
    if(Q->front==Q->rear)
        return ERROR;
    else
    {
        p = Q->front->next;
    }
    return p->data;
}

void print(linkqueue *Q)
{
    int i=0;
    linknode *p;
    if(Empty(Q))
        printf("队为空！");
    else
    {
        printf("队内元素为：");
        for(p=Q->front->next;i<n; i++,p=p->next)
        {
            printf("%d ",p->data);
        }
        printf("\n队内元素个数为%d个",n);

    }
}




int main(void)
{
    linkqueue q;
    linkqueue *Q;
    Q=&q;
    int i,e;
    printf("1.链队初始化\n2.链队判空\n3.进队\n4.出队\n5.队顶\n6.遍历队\n7.退出\n\n\n");
    while(scanf("%d", &i)!=EOF)
    {
        switch(i)
        {
            case 1:
                if(initial(Q))
                    printf("初始化成功！");
                break;

            case 2:
                if(Empty(Q))
                    printf("队空！");
                else
                    printf("队未空！");
                break;

            case 3:
                if(push(Q))
                    printf("进队成功！");
                break;

            case 4:
                if(pop(Q))
                    printf("出队成功！");
                else
                    printf("队为空！");
                break;
            case 5:
                if(!gettop(Q))
                    printf("队为空");

                else
                       {
                           e=gettop(Q);
                           printf("队顶元素为%d",e);
                       }
                       break;
            case 6: print(Q);break;
            case 7: exit(0);
        }
        putchar(10);
    }
}

问题不大，主要是pop函数内，一个if判断表达式写成赋值表达式了。 注意是pop函数内的这句:

 if(Q->front->next == Q->rear)