c - 实现链表 C

Question

我正在做作业，我想我应该使用链表来存储一些数据。问题是列表没有保留所有节点。

当添加完成并尝试查看节点时，它只显示添加到列表中的最后一个节点。

我会在下面写相关的部分，希望有人指出问题所在。

另外我应该指出，我测试过，在添加数据时打印数据，它确实表明它们被正确地添加到列表中)。

/**
 * Adds command name and it's hash onto the linked list
 * returns 1, if successful
 * returns 0, if failed
 */

int addToList(struct CMDList *head, char *pathCommand[], char *hash){

int result = 0;

/** If head was pointing to NULL, list empty, add at the beginning */
if(head->path == NULL){

    head->path = pathCommand[0];
    head->command = pathCommand[1];
    head->hash = hash;
    head->next = NULL;
    result = 1;

}else{

    struct CMDList *current = head;

    /** Find tail of the list */
    while(current->next != NULL){

        current = current->next;
    }
    current->next = (struct CMDList *)malloc(sizeof(struct CMDList));
    if(current->next != NULL){

        current->path = pathCommand[0];
        current->command = pathCommand[1];
        current->hash = hash;
        current->next = NULL;
        result = 1;

    }

}

return result;

}

主程序:

int main(int argc, char *argv[]){

/** CODE DELETED */

/** initialize list for storing cmds from config file */
/** cmdList is the head node that i use to traverse the list */
cmdList = (struct CMDList *)malloc(sizeof(struct CMDList));
if(cmdList != NULL){

    cmdList->path = NULL;
    cmdList->command = NULL;
    cmdList->hash = NULL;
    cmdList->next = NULL;
}else{

    printError("Silent Exit: couldn't initialize list to store commands of config file");
    exit(1);
}


/** CODE DELETED **/

/** add new data to the list */
if(!addToList(cmdList,arrayCommand,sha)){

        printError("Silent Exit: couldn't add to list");
        exit(1);
}

}

Answer 1

在这部分代码中:

if(current->next != NULL){

    current->path = pathCommand[0];
    current->command = pathCommand[1];
    current->hash = hash;
    current->next = NULL;
    result = 1;

}

你必须使用 current->next->... 而不是 current->...，因为你的新元素在 current->next，而不是 current(实际上，您检查了 current->next != NULL)。

由于这个错误，添加的第一个元素没问题，但是当您尝试添加第二个元素时，您只是分配了它的空间，然后覆盖了第一个元素。