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Differences between C and C++ linkage and calling conventions can also have subtle implications for code that uses function pointers. Some compilers will produce non-working code if a function pointer declared extern "C" points to a C++ function that is not declared extern "C". [22] For example, the following code:
For example, vfprintf() is an alternate version of fprintf() expecting a va_list instead of the actual unnamed argument list. A user-defined variadic function can therefore initialize a va_list variable using va_start and pass it to an appropriate standard library function, in effect passing the unnamed argument list by reference instead of ...
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.
Or there must be a declaration of the variable, with the keyword extern, inside the function. The static keyword (static and extern are mutually exclusive), applied to the definition of an external variable, changes this a bit: the variable can only be accessed by the functions in the same module where it was defined. But it is possible for a ...
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 ...
This can be understood as taking a null pointer of type structure st, and then obtaining the address of member m within said structure. While this implementation works correctly in many compilers, it has generated some debate regarding whether this is undefined behavior according to the C standard, [2] since it appears to involve a dereference of a null pointer (although, according to the ...
In C and C++, constructs such as pointer type conversion and union — C++ adds reference type conversion and reinterpret_cast to this list — are provided in order to permit many kinds of type punning, although some kinds are not actually supported by the standard language.
The original, pre-standard scheme is known as the ARM model, and is based on the name mangling described in the C++ Annotated Reference Manual (ARM). With the advent of new features in standard C++, particularly templates , the ARM scheme became more and more unsuitable – it could not encode certain function types, or produced identically ...