C Structures

Declaring a structure

You define a structure with the struct keyword, followed by a name and a list of members inside curly braces. Each member is just a normal variable declaration. The definition itself does not create any storage; it only describes the shape of the data.

#include <stdio.h>

struct Car {
    char brand[20];
    int year;
    float price;
};

int main() {
    struct Car myCar = {"Toyota", 2022, 25000.0};

    printf("Brand: %s\n", myCar.brand);
    printf("Year: %d\n", myCar.year);
    printf("Price: %.2f\n", myCar.price);
    return 0;
}

Once you have a struct variable, you reach its members with the dot operator. So myCar.year reads the year field, and you can assign to it the same way.

Setting members one at a time

You do not have to fill in everything at declaration time. You can create the struct first and assign values later, member by member. Note that for string members you use strcpy rather than plain assignment.

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

struct Point {
    int x;
    int y;
};

int main() {
    struct Point p;
    p.x = 4;
    p.y = 7;

    printf("Point is (%d, %d)\n", p.x, p.y);
    return 0;
}

• Use the dot operator (.) to access members of a struct variable.
• Members can be of any type, including arrays and other structs.
• Copying one struct into another with = copies all its members at once.
• String members need strcpy, since you cannot assign an array with =