Question

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>


typedef struct user {
    char *username;
    struct sockaddr_in addr;
} user;

user* users;

typedef struct room
{
  char *roomname;
  user* users;
} room;

room* rooms;

int addToUsersArray(char *username) {
    int i = 0;

    for(; i<10; i++) {
            if(users[i].username=='\0') {
                    users[i].username = username;
                return 1;
            } else if(strcmp(users[i].username, username) == 0)
                return -1;
    }
    return -1;
}


void initUsersArray() {  
    users = (user*) calloc(10, sizeof(user)); 
}

void initRoomsArray() {  
rooms = (room*) calloc(10, sizeof(room));
    int i =0;   
    for(;i<10;i++)      
         rooms[i].users = (user*) calloc(10,sizeof(user));  
}

int addToRoomsArray(char *roomname) {
    int i = 0;

    for(; i<10; i++) {
            if(rooms[i].roomname=='\0') {
                    rooms[i].roomname = roomname;
                return 1;
            } else if(strcmp(rooms[i].roomname, roomname) == 0)
                return -1;
    }
    return -1;
}

int addUserToRoom(char *roomname, user usr) {
    int i = 0;
    int k = 0;

    for(; i<10; i++) {
            if(rooms[i].roomname=='\0') {
                    rooms[i].roomname = roomname;
                    return 1;
            } else if(strcmp(rooms[i].roomname, roomname) == 0) {
            for(;k<10;k++) {
                if(rooms[i].users[k].username==NULL) { //This line makes trouble
                    rooms[i].users[k] = usr;
                }
            }
        }

    }
    return -1;
}


int main(int argc, char** argv) {
    initUsersArray();  
    initRoomsArray();      
    char *username = "Max";
    addToUsersArray(username);
    username = "Ma1x";
    addToUsersArray(username);
    printf("%s\n",users[0].username);
    printf("%s\n",users[1].username);

struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(4444);
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");  

char *room = "sportchat";
addToRoomsArray(room);
room = "berlinchat";
addToRoomsArray(room);

    printf("%s\n",rooms[0].roomname);
    printf("%s\n",rooms[1].roomname);

user michi;
michi.username = "michi";
michi.addr = addr;

struct sockaddr_in addr2;
    addr2.sin_family = AF_INET;
    addr2.sin_port = htons(1234);
    addr2.sin_addr.s_addr = inet_addr("127.0.1.1");

user willi;
willi.username = "willi";
willi.addr = addr2;

addUserToRoom(room,michi);
addUserToRoom(room,willi);


    return 1;
}

运行addUserToRoom（room，michi）时出现分段错误。使用结构我仍然有点不确定。在评论rooms[i].users[k] = usr;时，分段错误消失。我在unix系统上使用gcc。 gcc是否用空块分析if-expression？

修改如何实现可变数量的用户和房间？我想我必须使用realloc。但是怎么样？此致

Answer 1

你永远不会分配内存，也不会初始化

room.users

因此，当您尝试访问房间[i] .users [k]时，会出现分段错误。

作为旁注：不要使用GLOBALS，否则你会做愚蠢的事情（当你使用与你的结构成员同名的全局变量时更是如此）。此外，始终在for循环的第一部分初始化迭代变量。（你知道人们的死亡人数少于这个吗？：P）

这是一个主要功能的例子：

int main() {
    room* rooms;
    user* users;

    initUsersArray(users);
    initRoomsArray(rooms);

    char *username = "Max";
    addToUsersArray(users,username);
    username = "Ma1x";
    addToUsersArray(users,username);
    printf("%s\n",users[0].username);
    printf("%s\n",users[1].username);

    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(4444);
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    char *room = "sportchat";
    addToRoomsArray(rooms,room);

    /* ... */

    return 1;
}

Answer 2

该代码存在几个问题。要回答这个问题，您尚未分配rooms[i].users数组。

struct中的结构数组

2 个答案: