10. Structures, Unions, and Enumerations

Grouping related data with struct, sharing memory with union, and naming constants with enum in C.

Group related data with struct, share memory with union, and name integral constants with enum.

Examples

Student Records (student_records.c)

Demonstrates typedef struct, arrays of structs, and accessing members with the arrow operator:

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

#define MAX 3

typedef struct {
    char name[32];
    int age;
    double gpa;
} Student;

void print_student(const Student *s) {
    printf("%s (age %d) GPA %.2f\n", s->name, s->age, s->gpa);
}

int main(void) {
    Student cls[MAX];

    for (int i = 0; i < MAX; i++) {
        printf("Student %d name: ", i+1);
        fgets(cls[i].name, sizeof cls[i].name, stdin);
        size_t len = strlen(cls[i].name);
        if (len>0 && cls[i].name[len-1]=='\n') cls[i].name[len-1]='\0';
        printf("Age: "); scanf("%d", &cls[i].age);
        printf("GPA: "); scanf("%lf", &cls[i].gpa);
        int c; while ((c=getchar())!='\n' && c!=EOF) { }
    }

    printf("\nClass list:\n");
    for (int i = 0; i < MAX; i++) print_student(&cls[i]);

    return 0;
}