Defining structs
- C++ course
- Beginner
- Lesson 94/116
- 5 min
Learn to define a struct that combines multiple fields.
struct: grouping data
A struct groups data of different types under one roof. It starts with the struct keyword and members go inside curly braces; a semicolon at the end is mandatory.
struct Point {
int x;
int y;
};Here struct Point is a new type with two int members. This lets you manage the two coordinates of a point together. The same approach can model many real objects like student, book or product.
Defining members
Struct members are written inside curly braces like normal variable declarations. Each member has its own type and name. Member names must be unique within the same struct.
struct Book {
string title;
int year;
double price;
};Here title is a string, year is an integer, price is a double. To access a member you use the . operator; we will see this in the next lesson. In C++ struct members are accessible from outside by default.
Practice Define the Book struct
Define struct Book. It should have string title;, int year; and double price; members. Do not forget the semicolon at the end. In main, declare a Book b; variable and print cout << "Defined" << endl;.
Starter code
#include <iostream>
#include <string>
using namespace std;
// Define the Book struct
int main() {
// declare Book b; and print
return 0;
}Sample solution
#include <iostream>
#include <string>
using namespace std;
struct Book {
string title;
int year;
double price;
};
int main() {
Book b;
cout << "Defined" << endl;
return 0;
}Expected output
Defined
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which keyword is used to declare a struct?
- type
- class
- struct Correct answer
- record
Explanation: In C++ the struct keyword declares a struct.
2 Fill in the blank: struct definition
struct Point {
int x;
int ____;
};struct Point {
int x;
int y;
};Explanation: The second member of Point is y.
3 Match concept to explanation
| Term | Meaning |
|---|---|
struct |
Struct keyword |
member |
Variable inside a struct |
{ } |
Surrounds members |