将 char* 转换为字符串，然后分配给结构成员 : initialization makes integer from pointer

Question

我将接收新用户的数据并使用 strtok() 解析它，它返回一个 char*。但是，我在将 char* 分配给 char[] 类型的结构成员时遇到问题。我在第 52 行收到警告:初始化从指针生成整数而不进行强制转换。我不明白为什么编译器认为我正在从指针生成整数。我以为我正在将字符串 (username) 分配给字符串类型 (char username[MAX_USERNAME_LEN + 1])。

有人可以详细说明我的错误(也许可以就如何实现我想要的结果提出建议)吗？提前致谢。

#include <stdio.h>  /* for printf() and fprintf() */
#include <sys/socket.h> /* for socket(), bind(), and connect() */
#include <arpa/inet.h>  /* for sockaddr_in and inet_ntoa() */
#include <stdlib.h> /* for atoi() */
#include <string.h> /* for memset() */
#include <unistd.h> /* for close() */

#define MAXPENDING 5    /* Maximum outstanding connection requests */
#define MAX_MSGS 25 /* Maximum number of messages a user can have in his/her
               inbox = maximum number of messages a user can have in
               his/her Sent folder */
#define MAX_MSG_LEN 500 /* Maximum message length in characters */
#define MAX_USERS 50    /* Maximum number of users that can exist */
#define SERVER_PORT 8000/* The server port number */
#define MAX_RCV_LEN 2048    /* Buffer size in bytes for messages received by socket */
#define MAX_USERNAME_LEN 32
#define MAX_PASSWORD_LEN 32


struct user{
    char username[MAX_USERNAME_LEN + 1];
    char password[MAX_PASSWORD_LEN + 1];
};

/* Array of users */
struct user users[MAX_USERS];
int numberOfUsers;

int main(void) {
    /* THIS WORKS */
    struct user alice = { .username = "alice", .password = "1234"};
    users[0] = alice;
    numberOfUsers ++;

    /* 
     * I will be receiving data for new users and parsing it using
     * strtok(), which returns a char*, so this is why I hoped to be
     * able to add new users in the following manner: */
    char recvBuffer[MAX_RCV_LEN + 1] = "03::billy::1234::";
    char* opCodePtr = strtok(recvBuffer, "::");
    char* usernamePtr = strtok(NULL, "::");
    char* passwordPtr = strtok(NULL, "::");

    char username[MAX_USERNAME_LEN + 1];
    strncpy(username, usernamePtr, MAX_USERNAME_LEN);

    char password[MAX_PASSWORD_LEN + 1];
    strncpy(password, passwordPtr, MAX_PASSWORD_LEN);

    /* The following line gives me the Warning: initialization makes
       integer from pointer without a cast */
    struct user newUser = {.username = username, .password = password};
    users[numberOfUsers] = newUser;
    numberOfUsers ++;

    for (int i = 0; i < numberOfUsers; i ++)
        printf("USER = %s, PASS = %s\n", users[i].username, users[i].password);

    return 0;
}

输出:

USER = alice, PASS = 1234
USER = �, PASS = p 

Answer 1

username 是指向某处某些字符的指针，.username 是一个字符数组。您不能仅通过array = point 填充数组。您需要执行类似 strncpy(array,pointer, size) 的操作。

请注意，我不知道使用 strtok 返回的 char* 有多安全，因为 strtok 修改了字符串因为它是代币化的，所以我怀疑你保存所有代币所得到的结果实际上可能不会是你所期望的。