C++
- Getting started with C++
- Awesome Book
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- Alignment
- Argument Dependent Name Lookup
- Arithmitic Metaprogramming
- Arrays
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- Basic input/output in c++
- Basic Type Keywords
- Bit fields
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- C incompatibilities
- C++ Containers
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- C++ function "call by value" vs. "call by reference"
- C++ Streams
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- Concurrency With OpenMP
- Const Correctness
- const keyword
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- constexpr
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- 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
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- Friend keyword
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- Futures and Promises
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- Internationalization in C++
- Iteration
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- More undefined behaviors in C++
- Move Semantics
- mutable keyword
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- One Definition Rule (ODR)
- Operator Overloading
- operator precedence
- Optimization
- Optimization in C++
- Overload resolution
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- Pimpl Idiom
- Pointers
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- Recursion in C++
- Recursive Mutex
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- Return Type Covariance
- Returning several values from a function
- RTTI: Run-Time Type Information
- Scopes
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- 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
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- std::forward_list
- std::function: To wrap any element that is callable
- std::integer_sequence
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- std::string
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- Storage class specifiers
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- The ISO C++ Standard
- The Rule of Three, Five, And Zero
- The This Pointer
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- Trailing return type
- type deduction
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- Undefined Behavior
- Access to nonexistent member through pointer to member
- Accessing a dangling reference
- Accessing an object as the wrong type
- Accessing an out-of-bounds index
- Calling (Pure) Virtual Members From Constructor Or Destructor
- Deleting a derived object via a pointer to a base class that doesn't have a virtual destructor.
- Destroying an object that has already been destroyed
- Extending the `std` or `posix` Namespace
- Floating point overflow
- Function call through mismatched function pointer type
- Incorrect pairing of memory allocation and deallocation
- Infinite template recursion
- Integer division by zero
- Invalid base-to-derived static cast
- Invalid derived-to-base conversion for pointers to members
- Invalid pointer arithmetic
- Modifying a const object
- Modifying a string literal
- Multiple non-identical definitions (the One Definition Rule)
- No return statement for a function with a non-void return type
- Overflow during conversion to or from floating point type
- Reading or writing through a null pointer
- Returning from a [[noreturn]] function
- Shifting by an invalid number of positions
- Signed Integer Overflow
- Using an uninitialized local variable
- 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++ Undefined Behavior Accessing a dangling reference
Example
It is illegal to access a reference to an object that has gone out of scope or been otherwise destroyed. Such a reference is said to be dangling since it no longer refers to a valid object.
#include <iostream>
int& getX() {
int x = 42;
return x;
}
int main() {
int& r = getX();
std::cout << r << "\n";
}
In this example, the local variable x goes out of scope when getX returns. (Note that lifetime extension cannot extend the lifetime of a local variable past the scope of the block in which it is defined.) Therefore r is a dangling reference. This program has undefined behavior, although it may appear to work and print 42 in some cases.
