C + + pointer functions and function pointers

The function return type is divided into

1. Returns the base data type
2. (pointer function) returns a pointer type that returns a new pointer to a pointer that returns a worthwhile address//pointer function that cannot return a local amount (variable within a function)
3. Returns the reference type, and the address//reference function that returns the return value directly cannot return a reference to the local amount (variable within the function) without generating a copy. Returning a reference is more straightforward and more readable than returning a pointer

Types of Functions refers to the interface of a function, including the parameter definition and return type of a function

such as the function double Max (double,double);

Double (double,double);

Defining methods

typedef type function type name (formal parameter table)

such as: typedef double Functiontype (double,double);

Use:

such as: Functiontype max,min,average;

(equivalent to declaring three functions at the same time double Max (double,double);d ouble min (double,double); double average (double,double);)

function Pointers is a pointer variable that points to a function

Defining methods

1. Type (* pointer variable name) (formal parameter list)
2. function type * pointer variable name

such as: Double (*FP) (double,double);

Functiontype *FP;

When a function pointer is used as a function parameter, the address of the function can be passed, and different functions are called through the arguments.

Example:

1#include <iostream>2 using namespacestd;3 //Defining the Functiontype function type4typedefDoubleFunctiontype (Double,Double);5 //declaration of three functions min max average6 Functiontype min,max,average;7 //defining function Pointers FP8Functiontype *FP;9 //function callfunction with function pointersTen DoubleCallFunction (Functiontype *,Double,Double); One intMain () A { -     DoubleA=4.3, b=3.6; -cout<<"min ="<<min (b) <<"\tmax ="<<max (b) <<"\tave ="<<average (b) <<Endl; the     //function pointer get function address -Fp=min; cout<<"*fb min ="<<callfunction (fp,a,b); -Fp=max; cout<<"\T*FB max ="<<callfunction (fp,a,b); -Fp=average; cout<<"\T*FB Ave ="<<callfunction (fp,a,b) <<Endl; +cout<<"Call min ="<<callfunction (min,a,b); -cout<<"\tcall max ="<<callfunction (max,a,b); +cout<<"\tcall Ave ="<<callfunction (average,a,b) <<Endl; A  atCin.Get(); -     return 0; - } - DoubleMinDoubleADoubleb) - { -     returnA>b?b:a; in } - DoubleMaxDoubleADoubleb) to { +     returnA>b?a:b; - } the DoubleAverageDoubleADoubleb) * { $     return(A+B)/2;Panax Notoginseng } - DoubleCallFunction (Functiontype *FP,DoubleADoubleb) the { +     returnFP (A, b); A}

C + + pointer functions and function pointers