Function pointer Basics

# Include <iostream> <br/> using namespace STD; <br/> typedef void (* fcnptr) (Int &); // C ++ primer, this definition indicates that fcnptr is a pointer type Name Pointing to the function, this pointer is a pointer to a function with a return value of void and an int & parameter. <br/> // This method is useful for defining synonyms, because the function pointer type is often very lengthy <br/> // example function <br/> void print (Int & Data) <br/>{< br/> cout <data <Endl; <br/>}< br/> // example function <br/> void add_one (Int & Data) <br/>{< br/> data ++; <br/>}< br/> // generic container. To demonstrate how to encapsulate data and provide data utilization, <br/> temp Late <class T> <br/> class container <br/>{< br/> Public: <br/> container (); <br/> container (INT length, t arr []); <br/> void for_each (void (*) (T &); // provides an interface for Traversing data <br/> PRIVATE: <br/> int length; <br/> T * data; <br/> }; <br/> // define <br/> template <class T> <br/> container <t>: container () <br/>{< br/> length = 0; <br/> }; <br/> // define <br/> template <class T> <br/> container <t>: container (INT length, t arr []) <Br/>{< br/> This-> length = length; <br/> DATA = new T [This-> length]; <br/> for (INT I = 0; I <length; I ++) <br/>{< br/> data [I] = arr [I]; <br/>}< br/> //!!! Are there any comparisons? <Br/> // The parameter declared in the class is void (*) (T &) <br/> // void (* visit) (T &) is defined here &) <br/> // Lenovo ing... <br/> // previously, we can declare POP (INT) in this way, and then pop (INT t) during implementation) <br/> // Therefore, the parameter type is int, and the object name is T <br/> // so ..., likewise... <br/> // The above function pointer type is void (*) (T &), that is, return type + (*) + function parameter list <br/> // the pointer name is visit <br/> template <class T> <br/> void container <t> :: for_each (void (* visit) (T &) <br/>{< br/> for (INT I = 0; I <length; I ++) <br/>{< br/> visit (data [I]); <br/>}< br/> int main () <br/>{< br/> int arr [5] = {1, 2, 3, 4, 5 }; <br/> container <int> int_container (5, arr); <br/> int_container.for_each (print); // C ++ primer, when the function name is referenced but the function is not called, the function name is automatically interpreted as a pointer to the function <br/> fcnptr p = 0; // C ++ primer, function pointers can only be initialized or assigned values using the same type, function pointers, or 0-means expressions <br/> P = add_one; // Chen zhipeng, the same type indicates that the returned type is the same as the parameter list, so you can also p = print <br/> I Nt_container.for_each (p); // play, call add_one <br/> int_container.for_each (print); // play, call print to continue output <br/> return 0; <br/>}< br/> // thank you! <Br/>

all is over!