Structures

C

Reference manual

@see typedef keyword

Structures are a fundamental feature in C programming. They allow you to group related variables together under a single user-defined data type, facilitating organization and manipulation of complex data.

Syntax

On the following example we define two structures Date and Person. The struct Date holds three variables of type int, one for the day, one for the month and one for the year, The struct Person holds a char array for the name, a float variable for the height and an instance of the Date struct for the birth date.

To initialize the data of a struct we separate the values of the members by commas in the order in which they were defined and we enclose them in braces: { value1, value2, ... }.

To access a member of a struct we use the name of the instance followed by the dot operator (.) followed by the name of the member: person.name. If the instance of the struct is a pointer we use the arrow operator (->) instead of the dot operator (.): date->day.

To make the use of struct more readable, the typedef keyword can be employed to define an alias for a structure.

#include <stdio.h>

struct Date
{
    int day;
    int month;
    int year;
};

struct Person 
{
    char name[60];
    float height;
    struct Date birth_date;
};

void print_date(struct Date *date);

int main(void)
{
    struct Person person = {"Mike", 1.76, {12, 4, 1989}};
    printf("Name: %s\n", person.name);
    printf("Height: %.2f\n", person.height);
    print_date(&person.birth_date);
    return (0);
}

void print_date(struct Date *date)
{
    printf("Birth Date Day: %d\n", date->day);
    printf("Birth Date Month: %d\n", date->month);
    printf("Birth Date Year: %d\n", date->year);
}