传递结构的字段名称以在函数内部访问 [英] Pass the field name of struct to access inside a function

问题描述

我有一个链表，我做了一个函数来获取一个节点.但我想同时使用它来按名字或姓氏进行搜索.

I have a linked list and I made a function to fetch a node. But I want to use it both to search by first or last name.

typedef struct people {
   char name[60],
        lastname[60];
   struct people *next;
} people;

people *search(const char *key, people *list, FIELD) {
    while (list && strcmp(key, list->FIELD) != 0) {
        list = list->next;
    }
    return list;
}

示例:

people *aux;
aux = search("John", list_of_people, "name");

或者:

aux = search("Smith", list_of_people, "lastname");

有没有一种清晰有效的方法来解决这个问题而不需要重复代码?

There is a clear and efficient way to solve this problem without repeating code?

推荐答案

use offsetof() 宏.

例如:

people *search(const char *key, people *list, size_t FIELD) {// FIELD is field offset,
    while (list && strcmp(key, (char*)list + FIELD) != 0) {
        list = list->next;
    }
    return list;
}

打电话

aux = search("John", list_of_people, offsetof(people, name));
aux = search("Smith", list_of_people, offsetof(people, lastname));

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