如何判断是否为回文字符串

Question

为什么这里不能正确判断是否为回文字符串

#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#define max 100

typedef struct
{
    char data[max];
    int front;
    int rear;
}queque;

typedef struct
{
    char data[max];
    int size;
}stack;

void initque(queque* q)
{
    q->front = q->rear = 0;
}

void initstack(stack* s)
{
    s->size = 0;
}

void push(stack* s, char x)
{
    if (s->size == max)
    {
        printf("栈满了\n");

    }
    else
    {
        s->data[s->size] = x;
        s->size = (s->size + 1);

    }
}

char popstack(stack* s)
{
    char z;
    if (s->size == 0)
    {
        printf("栈空\n");
        return '0';
    }
    else
    {
        z = s->data[s->size];
        s->size = (s->size - 1);
        return z;
    }
}

void enterque(queque* q, char x)
{
    if ((q->rear + 1) % max == q->front)
    {
        printf("队列已满\n");

    }
    else
    {
        q->data[q->rear] = x;
        q->rear = (q->rear + 1);
    }
}

char popque(queque* q)
{
    char c;
    if (q->front == q->rear)
    {
        printf("队列为空\n");
        return '0';
    }
    else {
        c = q->data[q->front];
        q->front = (q->front + 1);
        return c;
    }
}
int define(stack* s, queque* q)
{
    char v;
    int flag = 1;
    printf("请输入需要判断回文的字符串：\n");
    while ((v = getchar()) != '\n')
    {
        push(s, v);
        enterque(q, v);
    }
    while (q->front == q->rear)
    {
        if (popstack(s) != popque(q))
        {
            flag = 0;
            break;
        }

    }
    if (flag == 1) printf("是回文字符串\n");
    else printf("不是回文字符串\n");
    return 0;
}

int main(void)
{
    stack* s = (stack*)malloc(sizeof(stack));
    queque* q = (queque*)malloc(sizeof(queque));
    initstack(s);
    initque(q);
    define(s, q);
    return 0;
}

Answer 1

两个问题 ，代码中已注释

#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.,h>
#include <stdlib.h>
#define max 100
typedef struct
{
    char data[max];
    int front;
    int rear;
}queque;
typedef struct
{
    char data[max];
    int size;
}stack;
void initque(queque* q)
{
    q->front = q->rear = 0;
}
void initstack(stack* s)
{
    s->size = 0;
}
void push(stack* s, char x)
{
    if (s->size == max)
    {
        printf("栈满了\n");
    }
    else
    {
        s->data[s->size] = x;
        s->size = (s->size + 1);
    }
}
char popstack(stack* s)
{
    char z;
    if (s->size == 0)
    {
        printf("栈空\n");
        return '0';
    }
    else
    {
        z = s->data[s->size-1];   //这里要改成 s->size-1，因为s->size表示元素数量，减去1才是下标
        s->size = (s->size - 1);
        return z;
    }
}
void enterque(queque* q, char x)
{
    if ((q->rear + 1) % max == q->front)
    {
        printf("队列已满\n");
    }
    else
    {
        q->data[q->rear] = x;
        q->rear = (q->rear + 1);
    }
}
char popque(queque* q)
{
    char c;
    if (q->front == q->rear)
    {
        printf("队列为空\n");
        return '0';
    }
    else {
        c = q->data[q->front];
        q->front = (q->front + 1);
        return c;
    }
}
int define(stack* s, queque* q)
{
    char v;
    int flag = 1;
    printf("请输入需要判断回文的字符串：\n");
    while ((v = getchar()) != '\n')
    {
        push(s, v);
        enterque(q, v);
    }
    while (q->front != q->rear)   //这里要改为 !=，表示队列元素尚未比较完成
    {
        if (popstack(s) != popque(q))
        {
            flag = 0;
            break;
        }
    }
    if (flag == 1) printf("是回文字符串\n");
    else printf("不是回文字符串\n");
    return 0;
}
int main(void)
{
    stack* s = (stack*)malloc(sizeof(stack));
    queque* q = (queque*)malloc(sizeof(queque));
    initstack(s);
    initque(q);
    define(s, q);
    return 0;
}