C:如何在函数中返回tree_node

Question

我正在构建一个目录树。

我正在尝试复制外壳"cd"命令以输入目录。

如何tree_node cwd 设为子目录后返回 cwd？

（cwd = 当前工作目录，subDir = 子目录）例如：

cwd = 子目录->树;

返回CWD;（如何返回 CWD 而没有错误？

// *checks whether cwd has a subdirectory named arg
// *if yes, the function returns the corresponding tree node (and become new working directory)
// *if no, prints an error message
// *handle cd and cd ..
struct tree_node *do_cd(struct tree_node *cwd, struct tree_node *root, char *arg) {
    // checks if directory exists
    struct list_node *subDir = cwd -> first_child;
    while (subDir != NULL) {
        if (strcmp(subDir->tree->string_buffer, arg) == 0) {
            printf("Entering directory with name %s n", arg);
            subDir->tree = cwd;
            return cwd;
            printf("Directory with name %sentered.n", arg);
        }
        subDir = subDir->next;
    }
    printf("Directory does not exist!n");
}

Answer 1

您需要返回 NULL 或任何指向有效树的指针。您可以检查此代码：

struct tree_node *do_cd(struct tree_node *cwd, struct tree_node *root, char *arg) {
// checks if directory exists
struct list_node *subDir = cwd -> first_child;
while (subDir != NULL) {
    if (strcmp(subDir->tree->string_buffer, arg) == 0) {
        printf("Entering directory with name %s n", arg);
        subDir->tree = cwd;
        printf("Directory with name %sentered.n", arg);
        return cwd;
    }
    subDir = subDir->next;
}
printf("Directory does not exist!n");
return NULL;
}