学ぶ Struct with Arrays and Other Structs

セクション 1. 章 13

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In some structures, it becomes necessary to use an array of nested structures when one object contains multiple related sub-objects. For example, if a student can take several courses, it makes sense to represent the courses as an array of structures inside the Student structure.

Example syntax:

OuterStruct.NestedStruct[1].NestedField;

To access an element of the nested structure array, you first refer to the outer structure, then use an index to select the desired element of the array, and finally access a specific field of that element.

Practical Example

Imagine each student has a name, age, and a set of courses. Each course contains its title, instructor, and number of credits.

main.c


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

struct Course {
    char name[50];
    char instructor[50];
    int credits;
};

struct Student {
    char name[50];
    int age;
    struct Course courses[3]; // array of nested structures
};

int main() {
    struct Student student;

    // Initialize student
    strcpy(student.name, "Alice Johnson");
    student.age = 20;

    // Initialize courses
    strcpy(student.courses[0].name, "Mathematics");
    strcpy(student.courses[0].instructor, "Dr. Smith");
    student.courses[0].credits = 4;

    strcpy(student.courses[1].name, "Computer Science");
    strcpy(student.courses[1].instructor, "Prof. Brown");
    student.courses[1].credits = 3;

    strcpy(student.courses[2].name, "History");
    strcpy(student.courses[2].instructor, "Dr. Green");
    student.courses[2].credits = 2;

    // Display information
    printf("Student: %s\n", student.name);
    printf("Age: %d\n", student.age);
    printf("Courses:\n");
    for (int i = 0; i < 3; i++) {
        printf("  Course %d: %s, Instructor: %s, Credits: %d\n",
               i + 1,
               student.courses[i].name,
               student.courses[i].instructor,
               student.courses[i].credits);
    }

    // Example of accessing a specific nested field
    printf("\nInstructor of the second course: %s\n", student.courses[1].instructor);

    return 0;
}

In this example, the Student structure has a courses array with three elements of type Course. Each course has its own title, instructor, and number of credits. To access a specific course, use the array index and dot operator: student.courses[1].instructor.

Using arrays of nested structures is useful for representing objects with repeated sub-objects, such as students with courses, stores with products, or books with authors.

タスク

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The student is represented by a structure Student which contains a fixed-size array of nested structures Course. Each course has a name, instructor, and number of credits. The function should iterate through all courses and sum the credits.

Implement a function calculateTotalCredits with a return type of int.

Inside the function, create an int variable total initialized to 0.
Use a for loop to iterate from 0 to the number of courses (3).
For each course, access credits and add it to total.
Return the final value of total.

解答

実践的な練習のためにデスクトップに切り替える下記のオプションのいずれかを利用して、現在の場所から続行する

すべて明確でしたか？

フィードバックありがとうございます！

セクション 1. 章 13

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