C++
- Getting started with C++
- Awesome Book
- Awesome Community
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- Alignment
- Argument Dependent Name Lookup
- Arithmitic Metaprogramming
- Arrays
- Atomic Types
- Attributes
- auto
- Basic input/output in c++
- Basic Type Keywords
- Bit fields
- Bit Manipulation
- Bit Operators
- Build Systems
- C incompatibilities
- C++ Containers
- C++ Debugging and Debug-prevention Tools & Techniques
- C++ function "call by value" vs. "call by reference"
- C++ Streams
- C++11 Memory Model
- Callable Objects
- Classes/Structures
- Client server examples
- Common compile/linker errors (GCC)
- Compiling and Building
- Concurrency With OpenMP
- Const Correctness
- const keyword
- Constant class member functions
- constexpr
- Copy Elision
- Copying vs Assignment
- Curiously Recurring Template Pattern (CRTP)
- Data Structures in C++
-
Date and time using
header - decltype
- Design pattern implementation in C++
- Digit separators
- Enumeration
- Exceptions
- Explicit type conversions
- Expression templates
- File I/O
- Floating Point Arithmetic
- Flow Control
- Fold Expressions
- Friend keyword
- Function Overloading
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- Futures and Promises
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- Internationalization in C++
- Iteration
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- Layout of object types
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- Memory management
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- More undefined behaviors in C++
- Move Semantics
- mutable keyword
- Mutexes
- Namespaces
- Non-Static Member Functions
- One Definition Rule (ODR)
- Operator Overloading
- operator precedence
- Optimization
- Optimization in C++
- Overload resolution
- Parameter packs
- Perfect Forwarding
- Pimpl Idiom
- Pointers
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- Polymorphism
- Preprocessor
- Profiling
- RAII: Resource Acquisition Is Initialization
- Random number generation
- Recursion in C++
- Recursive Mutex
- Refactoring Techniques
- References
- Regular expressions
- Resource Management
- Return Type Covariance
- Returning several values from a function
- RTTI: Run-Time Type Information
- Scopes
- Semaphore
- SFINAE (Substitution Failure Is Not An Error)
- Side by Side Comparisons of classic C++ examples solved via C++ vs C++11 vs C++14 vs C++17
- Singleton Design Pattern
- Smart Pointers
- Sorting
- Special Member Functions
- Standard Library Algorithms
- static_assert
- std::any
- std::array
- std::atomics
- std::forward_list
- std::function: To wrap any element that is callable
- std::integer_sequence
- std::iomanip
- std::map
- std::optional
- Introduction
- optional as return value
- Using optionals to represent the absence of a value
- Using optionals to represent the failure of a function
- value_or
- std::pair
- std::set and std::multiset
- std::string
- std::variant
- std::vector
- Storage class specifiers
- Stream manipulators
- Templates
- The ISO C++ Standard
- The Rule of Three, Five, And Zero
- The This Pointer
- Thread synchronization structures
- Threading
- Trailing return type
- type deduction
- Type Erasure
- Type Inference
- Type Keywords
- Type Traits
- Typedef and type aliases
- Undefined Behavior
- Unions
- Unit Testing in C++
- Unnamed types
- Unspecified behavior
- User-Defined Literals
- Using declaration
- Using std::unordered_map
- Value and Reference Semantics
- Value Categories
- Variable Declaration Keywords
- Virtual Member Functions
C++ std::optional value_or
Example
void print_name( std::ostream& os, std::optional<std::string> const& name ) {
std::cout "Name is: " << name.value_or("<name missing>") << '\n';
}
value_or either returns the value stored in the optional, or the argument if there is nothing store there.
This lets you take the maybe-null optional and give a default behavior when you actually need a value. By doing it this way, the "default behavior" decision can be pushed back to the point where it is best made and immediately needed, instead of generating some default value deep in the guts of some engine.
