Explore the full potential of C++ by mastering the standard library.

Become a C++ Programmer

The C++ standard library is a collection of all the tools and utilities available in C++. It received its latest update in 2017, known as C++17. The update introduces many new features that further optimize our code. This module will help us fully grasp C++ and use it to its full potential.

C++ Standard Library

[std::optional](http://en.cppreference.com/w/cpp/utility/optional) is quite comfortable for calculations such as database queries that may have a result. 

> 🔑 **Don't use no-results**
>\
> Before C++17 it was common practice to use a special value such as a null pointer, an empty string, or a unique integer to denote the absence of a result. These special values or no-results are very error-prone because you have to misuse the type system to check the return value. This means that for the type system that you have to use a regular value such as an empty string to define an irregular value.

The various constructors and the convenience function `std::make_optional` let you define an optional object `opt` with or without a value. `opt.emplace` will construct the contained value in-place and `opt.reset` will destroy the container value. You can explicitly ask a `std::optional` container if it has a value or you can check it in a logical expression. `opt.value` returns the value and `opt.value_or` returns the value or a default value. If `opt` has no contained value, the call `opt.value` will throw a `std::bad_optional_access` exception.
                                                                                                                     
Here is a short example of using `std::optional`.

std::optional is very convenient when the value of our object can be null or empty.

The Standard Library

Overview

Application of Libraries

Useful Functions

Adaptors for Functions

Pairs and Tuples

Reference Wrappers

Smart Pointers

Type Traits

Time Library

std::any, std::optional, and std::variant

Containers in General

Sequential Containers

Associative Containers in General

Ordered Associative Containers

Unordered Associative Containers

Adaptors for Containers

Iterators

Callable Units

Algorithms

Non-Modifying Algorithms

Modifying Algorithms

More Algorithms

New Algorithms with C++17

Numeric

Strings

String View

Regular Expressions

Input and Output Streams

Conclusion

std::optional