Differences between C++98, C++11, C++14, C++17, and C++20?

C++98

Key Features

• First Standardized Version:
  • Introduced in 1998.
• Standard Template Library (STL):
  • Provided containers (e.g., std::vector, std::map) and algorithms.
• Basic Exception Handling:
  • try, catch, and throw keywords for exception handling.
• Namespaces:
  • Prevented name collisions.
• Templates:
  • Enabled generic programming.
• bool Type:
  • Introduced bool type.

C++11

Key Features

• Smart Pointers:
  • std::unique_ptr, std::shared_ptr for better memory management.
• Move Semantics:
  • std::move, move constructors, and move assignment operators for efficient resource transfers.
• Lambda Expressions:
  • Anonymous functions for inline use.
• auto Keyword:
  • Automatic type deduction.
• Range-Based for Loops:
  • Simplified iteration over containers.
• nullptr Keyword:
  • Type-safe null pointer.
• Thread Support:
  • std::thread, std::mutex, std::lock_guard for multithreading.

Example: Lambda Expression

auto add = [](int a, int b) { return a + b; };

C++14

Key Features

• Improved Lambda Expressions:
  • Lambda capture by move.
• Generic Lambdas:
  • Type deduction for parameters.
• Return Type Deduction:
  • For functions with auto as return type.
• Variable Templates:
  • Templates for constants.

Example: Generic Lambda

auto add = [](auto a, auto b) { return a + b; };

C++17

Key Features

• std::optional:
  • Represents optional values.
• std::variant:
  • Type-safe union.
• std::any:
  • Holds single value of any type.
• If-Init Statements:
  • Initialize variables within if and switch.
• Structured Bindings:
  • Unpack tuples and structs into individual variables.
• Filesystem Library:
  • std::filesystem for file and directory operations.

Example: Structured Binding

std::tuple<int, int> getCoordinates() { return {1, 2}; }
auto [x, y] = getCoordinates();

C++20

Key Features

• Concepts:
  • Constraints for template parameters.
• Ranges:
  • Simplified operations on sequences.
• Coroutines:
  • Asynchronous programming.
• Modules:
  • Improved code modularization.
• Three-Way Comparison (Spaceship Operator):
  • operator<=> for automatic comparisons.
• Calendar and Time Zone Library:
  • Improved date and time handling.

Example: Concepts

template<typename T>
concept Addable = requires(T a, T b) { a + b; };

template<Addable T>
T add(T a, T b) { return a + b; }