C 中指针与整数的比较

Question

很难说出这里问的是什么。这个问题是含糊的、模糊的、不完整的、过于宽泛的或修辞性的，无法以目前的形式得到合理的回答。如需帮助澄清此问题以便重新打开它， visit the help center 。

已关闭 11 年前。

我试图在链表中搜索星号，但是每次我尝试使用 while 循环将头指针与星号进行比较时，程序都不会编译，说它无法将指针与整数进行比较

在打印列表功能中:while( pt != '*')

/*
 *Description: Construction of a social network
 */

#include < stdio.h>
#include < strings.h>
#include < stdlib.h>
#define SIZE 30
#define PEOPLE_SIZE 20
#define PRINT_NETWORK 1
struct people   
{
        char name[SIZE];
        int age;
        char gender[SIZE];
        int idnumber;
        struct friendlist *friends;
};

typedef struct friendlist
{
        int friendsname[PEOPLE_SIZE];
        struct friendlist *next;
        struct people *person;
}node_t;

void scan_friends(FILE *input2, node_t *pt)
{
        char *friend_name;
        fscanf(input2,"%s", &pt->friendsname);
}

void  print_friends(node_t pt)
{
       printf("%s ", pt.friendsname);
}

void print_list(node_t *pt)
{
        int friendsname[PEOPLE_SIZE];
        struct friendlist *next;
        struct people *person;

}node_t;

void  print_friends(node_t pt) 
{
        printf("%s ", pt.friendsname);
}

void print_list (node_t *pt)
{ 
        if (pt==NULL)
                printf("The list is empty\n");
        else
        {                 // traversing the list
                while (pt!=NULL)
                {
                        while (pt != '*')
                       {
                                    print_friends(*pt);
                                    pt=pt->next;
                       }
                }
        }
}

int main(void)
{
    int choice=0;
    FILE *input; //pointer to people.dat

    FILE *input_friends;
    int i=0;
    struct people people[SIZE];
    struct friendlist friendlist[PEOPLE_SIZE];
    node_t *headp, *temp, *current=NULL;
    char user_name[SIZE];
    int user;

            input_friends=fopen("friends.dat", "r"); //opens friends file

            while(!feof(input_friends))
            {
                    // create a new list element
                    temp = (node_t *)malloc(sizeof(node_t));  // memory
                    scan_friends(input_friends, temp);    // initialization of element 
                    temp->next=NULL;     // setting pointer to null.

                    if (current==NULL)
                    {
                            headp=temp;  // setting the head of the list
                    }
                    else
                    {
                                current->next=temp;   // else connecting to previous
                        }
                        current=temp;   // updating the current element

                        i++;   // count number of elements added
                }
                fclose(input_friends);
                print_list(headp);                                    
        }

        printf("\n");
        return(0);
}

Answer 1

这就是我认为您要发布的内容，但它仍然无法编译，因为您无法将指针与字符进行比较

/*
 *Description: Construction of a social network
 */

#include <stdio.h>
#include <strings.h>
#include <stdlib.h>
#define SIZE 30
#define PEOPLE_SIZE 20
#define PRINT_NETWORK 1

struct people   
{
    char name[SIZE];
    int age;
    char gender[SIZE];
    int idnumber;
    struct friendlist *friends;
};

typedef struct friendlist
{
    int friendsname[PEOPLE_SIZE];
    struct friendlist *next;
    struct people *person;
} node_t;

void scan_friends(FILE *input2, node_t *pt)
{
    char *friend_name;
    fscanf(input2,"%s", &pt->friendsname);
}

void  print_friends(node_t pt)
{
    printf("%s ", pt.friendsname);
}

void print_list (node_t *pt)
{ 
    if (pt==NULL)
        printf("The list is empty\n");
    else
    {                 // traversing the list
        while (pt!=NULL)
        {
            while (pt != '*')
            {
                print_friends(*pt);
                pt=pt->next;
            }
        }
    }
}

int main(void)
{
    int choice=0;
    FILE *input; //pointer to people.dat

    FILE *input_friends;
    int i=0;
    struct people people[SIZE];
    struct friendlist friendlist[PEOPLE_SIZE];
    node_t *headp, *temp, *current=NULL;
    char user_name[SIZE];
    int user;

    input_friends=fopen("friends.dat", "r"); //opens friends file

    while(!feof(input_friends))
    {
        // create a new list element
        temp = (node_t *)malloc(sizeof(node_t));  // memory
        scan_friends(input_friends, temp);    // initialization of element 
        temp->next=NULL;     // setting pointer to null.

        if (current==NULL)
        {
            headp=temp;  // setting the head of the list
        }
        else
        {
            current->next=temp;   // else connecting to previous
        }
        current=temp;   // updating the current element

        i++;   // count number of elements added
    }
    fclose(input_friends);
    print_list(headp);                                    

    printf("\n");
    return(0);
}

我的编辑已将其减少到只有一个编译错误，您需要自行解决。它在第 47 行:

while (pt != '*')

这当然不是您想要做的。

您想将什么与星号进行比较？名字？

考虑一些比如

while (pt->person->name != '*')

请注意，这仍然不起作用，因为您将比较字符数组与单个字符。但这应该会让您朝着您想要的方向前进，具体取决于您想要将星号与什么进行比较。请注意，这是访问您拥有指针的结构成员的方式。

其他内容只是结构的基础知识以及如何访问其成员。