c - 错误 : ‘::main’ must return ‘int’ void main(), 错误 : ‘strcmp’ was not declared in this scope z = strcmp(ch, ch1)？

Question

我必须生成一个反向链表，这些是我的先决条件

定义结构:

struct node
{
    int data;
    struct node * link;
}

包含函数

append --- 在链表末尾添加数据。

Reverse --- 反转链表。

显示---显示链表中的所有数据。

void append ( struct node **, int ) ;

void display ( struct node * ) ;

void reverse (struct node **); 

我收到的错误:

1.‘::main’ must return ‘int’
 void main()

2.‘strcmp’ was not declared in this scope
 z = strcmp(ch,ch1);

我的代码:

#include<stdio.h>
#include<stdlib.h>
struct node
{
    int data;
    struct node *link;
};
void append(struct node **head);
void reverse(struct node **head);
void display(struct node *p);
void main()
{
    struct node *p = NULL;
    append(&p);
    printf("The elements in the linked list are: ");
    display(p);
    printf("The elements in the reversed linked list are: ");
    reverse(&p);
    display(p);
}
void reverse(struct node **head)
{
    struct node *p,*q,*r;
    p=q=r=*head;
    p = p->link->link;
    q = q->link;
    r->link = NULL;
    q->link = r;
    while(p != NULL)
    {
        r = q;
        q = p;
        p = p->link;
        q->link = r;
    }
    *head = q;
}
void append(struct node **head)
{
    int c,z;
    char ch[10] = "Yes";
    char ch1[10];
    struct node *temp,*rear;
    do
    {
        printf("Enter the value:\n");
        scanf("%d",&c);
        temp = (struct node*)malloc(sizeof(struct node));
        temp->data=c;
        temp->link=NULL;
        if(*head == NULL)
        {
            *head = temp;
        }
        else
        {
            rear->link = temp;
        }
        rear = temp; 
        printf("\nDo you want to add another node? Type Yes/No\n");
        scanf("%s",ch1);
        z = strcmp(ch,ch1);
    }
    while(z == 0);
    printf("\n");
}
void display(struct node *p)
{
    while(p != NULL)
    {
        printf("%d ",p->data);
        p=p->link;
    }
    printf("\n");
}

Answer 1

更改void main()至int main(void)并添加#include <string.h>

main() 的有效签名是

1. int main(int argc, char **argv);
2. int main(void);

和strcmp() (以及所有 str* 函数)在 string.h 中声明)。