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, depending on the compiler and used optimization level, the compiler may interpret the conditional as always true (because func can be seen as undefined from a standards point of view). [7] An alternative to the above construct is using a system API to check if func is defined (e.g. dlsym with RTLD_DEFAULT ).
In the C++ programming language, a reference is a simple reference datatype that is less powerful but safer than the pointer type inherited from C.The name C++ reference may cause confusion, as in computer science a reference is a general concept datatype, with pointers and C++ references being specific reference datatype implementations.
In C/C++ bitwise shifting a value by a number of bits which is either a negative number or is greater than or equal to the total number of bits in this value results in undefined behavior. The safest way (regardless of compiler vendor) is to always keep the number of bits to shift (the right operand of the << and >> bitwise operators ) within ...
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types ...
A smart pointer typically uses reference counting to reclaim objects. Some other techniques include the tombstones method and the locks-and-keys method. [3] Another approach is to use the Boehm garbage collector, a conservative garbage collector that replaces standard memory allocation functions in C and C++ with a garbage collector. This ...
In the C and C++ languages, such non-portable constructs are generally grouped into three categories: Implementation-defined, unspecified, and undefined behavior. [3] The exact definition of unspecified behavior varies. In C++, it is defined as "behavior, for a well-formed program construct and correct data, that depends on the implementation."
A C++ closure may capture its context either by storing copies of the accessed variables as members of the closure object or by reference. In the latter case, if the closure object escapes the scope of a referenced object, invoking its operator() causes undefined behavior since C++ closures do not extend the lifetime of their context.
In C++, some constructs are specified to have undefined behavior. A compiler is free to implement any behavior or none, and typically an optimizing compiler will assume the code is unreachable. A compiler is free to implement any behavior or none, and typically an optimizing compiler will assume the code is unreachable.