EASYTUTORGUIDEC++ • C++23 / ISO/IEC 14882:2024

Classes and Objects

C++ Chapter 17 of 60. Beginner-to-advanced teaching with a code example for every topic.

5 topics5 code examples10 Q&A

17.1 Declaring Classes 17.2 Fields and State 17.3 Methods and Behavior 17.4 Constructors 17.5 Encapsulation

17.1 Declaring Classes

Declaring Classes is part of Classes and Objects. Learn what the construct does, the syntax it requires, how data moves through it, and the mistakes that can make the program incorrect or unsafe.

Why it matters

Use this feature when it makes the program clearer, safer, easier to maintain, or more efficient. Start with a small example before using it in a larger application.

Code example

#include <iostream>
#include <string>
class Person{public: std::string name; explicit Person(std::string n):name(std::move(n)){} }; int main(){Person p{"Ana"}; std::cout<<p.name;}

Step-by-step

Read the declarations and identify each value or object.
Follow execution from the first statement to the last.
Predict the output before running the example.
Run or compile it using the toolchain for this course.
Change one input and explain why the new result changes.

Expected result

The example should demonstrate Declaring Classes with a small, inspectable result. For platform-dependent or advanced examples, focus on the API pattern and verify the exact environment requirements.

Common mistakes

Common mistakes include using the feature before understanding lifetime/scope, ignoring errors, assuming conversions are harmless, or writing code that works only for one happy-path input.

Practice

Rewrite the example with different data. Add one edge case, predict the result, then test it. Explain the feature in your own words without looking at the lesson.

17.2 Fields and State

Fields and State is part of Classes and Objects. Learn what the construct does, the syntax it requires, how data moves through it, and the mistakes that can make the program incorrect or unsafe.

Why it matters

Use this feature when it makes the program clearer, safer, easier to maintain, or more efficient. Start with a small example before using it in a larger application.

Code example

#include <iostream>
int main(){ /* Fields and State */ std::cout<<"C++ example\n"; }

Step-by-step

Read the declarations and identify each value or object.
Follow execution from the first statement to the last.
Predict the output before running the example.
Run or compile it using the toolchain for this course.
Change one input and explain why the new result changes.

Expected result

The example should demonstrate Fields and State with a small, inspectable result. For platform-dependent or advanced examples, focus on the API pattern and verify the exact environment requirements.

Common mistakes

Common mistakes include using the feature before understanding lifetime/scope, ignoring errors, assuming conversions are harmless, or writing code that works only for one happy-path input.

Practice

Rewrite the example with different data. Add one edge case, predict the result, then test it. Explain the feature in your own words without looking at the lesson.

17.3 Methods and Behavior

Methods and Behavior is part of Classes and Objects. Learn what the construct does, the syntax it requires, how data moves through it, and the mistakes that can make the program incorrect or unsafe.

Why it matters

Use this feature when it makes the program clearer, safer, easier to maintain, or more efficient. Start with a small example before using it in a larger application.

Code example

#include <iostream>
int main(){ /* Methods and Behavior */ std::cout<<"C++ example\n"; }

Step-by-step

Read the declarations and identify each value or object.
Follow execution from the first statement to the last.
Predict the output before running the example.
Run or compile it using the toolchain for this course.
Change one input and explain why the new result changes.

Expected result

The example should demonstrate Methods and Behavior with a small, inspectable result. For platform-dependent or advanced examples, focus on the API pattern and verify the exact environment requirements.

Common mistakes

Common mistakes include using the feature before understanding lifetime/scope, ignoring errors, assuming conversions are harmless, or writing code that works only for one happy-path input.

Practice

Rewrite the example with different data. Add one edge case, predict the result, then test it. Explain the feature in your own words without looking at the lesson.

17.4 Constructors

Constructors is part of Classes and Objects. Learn what the construct does, the syntax it requires, how data moves through it, and the mistakes that can make the program incorrect or unsafe.

Why it matters

Use this feature when it makes the program clearer, safer, easier to maintain, or more efficient. Start with a small example before using it in a larger application.

Code example

#include <iostream>
#include <string>
class Person{public: std::string name; explicit Person(std::string n):name(std::move(n)){} }; int main(){Person p{"Ana"}; std::cout<<p.name;}

Step-by-step

Read the declarations and identify each value or object.
Follow execution from the first statement to the last.
Predict the output before running the example.
Run or compile it using the toolchain for this course.
Change one input and explain why the new result changes.

Expected result

The example should demonstrate Constructors with a small, inspectable result. For platform-dependent or advanced examples, focus on the API pattern and verify the exact environment requirements.

Common mistakes

Common mistakes include using the feature before understanding lifetime/scope, ignoring errors, assuming conversions are harmless, or writing code that works only for one happy-path input.

Practice

Rewrite the example with different data. Add one edge case, predict the result, then test it. Explain the feature in your own words without looking at the lesson.

17.5 Encapsulation

Encapsulation is part of Classes and Objects. Learn what the construct does, the syntax it requires, how data moves through it, and the mistakes that can make the program incorrect or unsafe.

Why it matters

Use this feature when it makes the program clearer, safer, easier to maintain, or more efficient. Start with a small example before using it in a larger application.

Code example

#include <iostream>
int main(){ /* Encapsulation */ std::cout<<"C++ example\n"; }

Step-by-step

Read the declarations and identify each value or object.
Follow execution from the first statement to the last.
Predict the output before running the example.
Run or compile it using the toolchain for this course.
Change one input and explain why the new result changes.

Expected result

The example should demonstrate Encapsulation with a small, inspectable result. For platform-dependent or advanced examples, focus on the API pattern and verify the exact environment requirements.

Common mistakes

Common mistakes include using the feature before understanding lifetime/scope, ignoring errors, assuming conversions are harmless, or writing code that works only for one happy-path input.

Practice

Rewrite the example with different data. Add one edge case, predict the result, then test it. Explain the feature in your own words without looking at the lesson.