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A function pointer, also called a subroutine pointer or procedure pointer, is a pointer referencing executable code, rather than data. Dereferencing the function pointer yields the referenced function, which can be invoked and passed arguments just as in a normal function call.
In the context of the language C, function arguments are pushed on the stack in the right-to-left (RTL) order, i.e. the last argument is pushed first. Consider the following C source code snippet: int callee ( int , int , int ); int caller ( void ) { return callee ( 1 , 2 , 3 ) + 5 ; }
How functions that take a variable number of arguments (variadic functions) are handled. Options include just passed in order (presuming the first parameter is in an obvious position) or the variable parts in an array. How return values are delivered from the callee back to the caller.
Notice that the type of the result can be regarded as everything past the first supplied argument. This is a consequence of currying, which is made possible by Haskell's support for first-class functions; this function requires two inputs where one argument is supplied and the function is "curried" to produce a function for the argument not supplied.
Pointers to functions (function pointers) are useful for passing functions as arguments to higher-order functions (such as qsort or bsearch), in dispatch tables, or as callbacks to event handlers. [37] A null pointer value explicitly points to no valid location. Dereferencing a null pointer value is undefined, often resulting in a segmentation ...
stdarg.h is a header in the C standard library of the C programming language that allows functions to accept an indefinite number of arguments. [1] It provides facilities for stepping through a list of function arguments of unknown number and type. C++ provides this functionality in the header cstdarg.
Function epilogue reverses the actions of the function prologue and returns control to the calling function. It typically does the following actions (this procedure may differ from one architecture to another): Drop the stack pointer to the current base pointer, so room reserved in the prologue for local variables is freed.
Because default arguments' values are "filled in" at the call site rather than in the body of the function being called, virtual functions take their default argument values from the static type of the pointer or reference through which the call is made, rather than from the dynamic type of the object supplying the virtual function's body.