Question

我有一个关于在C中更新数组的快速问题。我包括我编写的代码，以及调试/打印语句输出。

//struct
typedef struct Server {
char* name;
pid_t pid;
} Server;

//global vars
int num_servers; //the number of servers (num_servers-1 is index in  array)
Server* servers; //the array of servers
int size; //size of the array

//instantiation inside main method
num_servers = 0;
servers = NULL;  //null instantiation allows us to use realloc all time 
size = 0;

//inside main function and a while loop
//check if we need to resize the array
                if(num_servers >= size){
                    resizeArray(true);
                }
                //create struct
                Server s = createServer(args[3], id);
                //add to array
                insertServer(s);
                printf("Main: last server has name: %s\n", servers[num_servers-1].name); //debug
                ++num_servers;

/*
 * creates/returns a server with the specified characteristics
 * name - the name of server]
 * id - the id of the server
 */
Server createServer(char* name, pid_t id){
    Server s;
    s.name = malloc(strlen(name) * sizeof(char));
    strcpy(s.name, name);
    s.pid = id;
    printf("Created server with name: %s\n", s.name); //debug
    return s;
}

/*
 * appends server to end of array
 * serv - the server struct to insert
 */
int insertServer(Server serv){
    printf("Inserting server with name: %s\n", serv.name); //debug
    //allocate memory
    servers[num_servers-1].name = malloc(strlen(serv.name) * sizeof(char));
    //actually copy
    strcpy(servers[num_servers-1].name, serv.name);
    servers[num_servers-1].pid = serv.pid;
    printf("The last server in array now has id of: %s\n",   servers[num_servers-1].name);
    return 0;
}

当我第一次运行while循环并插入服务器时，程序正确运行（所有print语句都输出服务器的名称）。但是，只要while循环再次运行，我就会遇到一个seg错误。使用GDB我发现虽然数组的内存似乎已分配，但实际的结构（及其信息）不会出现在数组中。知道为什么信息在while循环期间存在于堆中，但是当它再次运行时消失了吗？谢谢。

Answer 1

在这段代码中你没有为c-string分配足够的内存（'\ 0'-char 又名终止 e的字符的遗忘字节）：

s.name = malloc(strlen(name) * sizeof(char));
strcpy(s.name, name);

尝试使用 strdup ：

s.name = strdup(name);

在c中更新动态数组

1 个答案: