如何从第二个结构访问第一个结构 - c

Question

所以这是代码，我无法理解。我无法理解的是如何进入结构城镇＆＃34;来自结构县。此外，我不知道如何在结构城镇写作以及如何访问它们。

#include <stdio.h>
#include <string.h>

struct town {
    char name[64];
    unsigned number;
};
struct country {
    char name[64];
    struct town capital;
    struct town *towns;
    unsigned number_of_towns;
};

int main() {
    struct country countries[5];
    for (int i = 0; i < 5; i++) {
        printf("Name of country: ");
        scanf("%s", countries[i].name);
        scanf("%s", countries->towns->name); //this is what i try.
    }

    getchar();
    getchar();


    return 0;
}

Answer 1

如何获取struct town类型的变量？

struct town v ;

如何访问它？

v.name[i] --> ith charcter of `name`
v.number

如何阅读？

scanf("%s",v.name);
scanf("%u",&v.number);

现在如何从其他结构中访问它们？

如果你使用指针struct town *，你需要一些东西，以便你可以指向它。您需要收集一些可用于存储信息的变量。

struct town capital;// it doesn't need to point to anyone.

struct town* towns; // I need variable(s) of type struct town so that I can point to it.

towns= malloc(sizeof (struct town)* AS_MANY_AS_YOU_NEED); //假设您分配4

您需要访问它们。

所以你做了什么？

您可以像这样访问每个struct town类型变量

town[i]然后您可以像我之前显示的那样访问它们。

我是否需要分配超过1个元素？

当然没有。你可以像

一样

towns = malloc(sizeof (struct town));

像towns[0]或*(towns+0)或*towns

一样访问它

什么是分配？

分配内存以存储来自免费存储空间的内容。

帮助我更多!!

好的，所以你在towns中分配了一些更多的变量，可以像towns[i]和

那样访问

它是

• 名称可以像towns[i].name一样访问。

• 号码可以在towns[i].number

中

• 特定城镇的name字符towns[i].name[i]

如何从各国访问它们？

  struct country {
        char name[64];        //countries[i].name
        struct town capital;  //countries[i].capital.name or countries[i].capital.number
        struct town *towns;   // (countries[i]->towns[i]).name or ...
        unsigned number_of_towns;
    } countries[5];

Answer 2

请尝试此代码可以帮助您。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

struct town {
    char name[64];
    unsigned number;
};
struct country {
    char name[64];
    struct town capital;
    struct town *towns;
    unsigned number_of_towns;
};

int main() {
    struct country countries[5];
    struct town *twn;
    for (int i = 0; i < 5; i++) {
        printf("Name of country: ");
        scanf("%s", countries[i].name);
        twn = malloc(sizeof(struct town));
        printf("Name of town 0: ");
        scanf("%s", twn->name);
        countries[i].towns = twn;
    }
    printf("*** Print Countries ***\n");
    for (int i = 0; i < 5; i++) {
        printf("Name of country: %s\n", countries[i].name);
        printf("Name of town 0: %s\n", countries[i].towns->name);
    }
    for (int i = 0; i < 5; i++) {
        free(countries[i].towns);
    }

    getchar();
    getchar();
    return 0;
}

测试

Name of country: one
Name of town 0: onetown
Name of country: two
Name of town 0: twotown
Name of country: three
Name of town 0: threetown
Name of country: four
Name of town 0: fourtown
Name of country: five
Name of town 0: fivetown
*** Print Countries ***
Name of country: one
Name of town 0: onetown
Name of country: two
Name of town 0: twotown
Name of country: three
Name of town 0: threetown
Name of country: four
Name of town 0: fourtown
Name of country: five
Name of town 0: fivetown