Four types of load changer in C + +

1. Type conversion

Static_cast<> (): Static type conversion, compile-time C + + compiler will do type checking, in C language, implicit type conversion, can use static_cast<> () for type conversion;

Reinterpret_cast<> (): coercion type conversion; compiler re-interpretation;

Dynamic_cast<cat *> (Base): Parent class object ===> sub-class object, downward transformation, generally used in inheritance;

Const_cast<> (): const char *---> char *, remove the constant attribute;

(1), the code is as follows:

#include <iostream>using namespace std;class Animal{    public:         virtual void cry ()  = 0;}; class dog : public animal{    public:         virtual void cry () {             cout<< "Wang Wang" <<endl;        }            void dohome () {             cout<< "housekeeping" &LT;&LT;ENDL;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;}        private:};class Cat : public Animal{     public:    virtual void cry () {         cout<< "Meow" <<endl;    }       void dothing () {         cout<< "Catch the Mouse" <<endl;    }    private :};void playobj (animal *base) {    base->cry ();    //1, inheritance   2, there is a virtual function of the rewrite  3, there is a parent pointer to a subclass object; ===> occurrence polymorphism     //dynamic_cast can recognize sub-class object, runtime type recognition;     Dog *pDog = dynamic_cast<Dog *> (base);   //is its own type, will convert successfully, Otherwise the return is Null;    if (Pdog) {        pdog->dohome ();    //let the dog do his peculiar work;    }    cat *pcat =  Dynamic_cast<cat *> (base);//Parent Object ===> sub-class object, downward transformation;     if (PCat) {         pcat->dothing ();    //let the cat do his peculiar work;     }}int main (void) { &Nbsp;  dog d1;    cat c1;    playobj (&AMP;D1);     playobj (&AMP;C1);    //animal *base = null;          //base = static_cast<Animal *> (&AMP;D1);     return 0;} /*int main (void) {    double pi = 3.14;    int  num2 = static_cast<int> (pi);  //static type conversion, compile-time C + + compiler will do type check, in C, implicit type conversion place, can use Static_ Cast<> () type conversion;    char *p1 =  "abcdef";     int  *p2 = NULL;    //p2 = static_cast<int*> (p1);  // Use static_cast, compiler compile, will do type check, if there is error, prompt error;     p2 = reinterpret_cast<int * > (p1);//  coercion type conversion; compiler re-interpretation     cout<<p1<<endl;    cout<<p2<<endl; //%d    return 0;} */

Operation Result:

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(2), the type conversion code for Const_cast<char *> (p):

#include <iostream>using namespace std;void printbuf (const char *p) {//p[1] = ' 1 ';    char *p1 = NULL;    P1 = Const_cast<char *> (p);//const char *---> char *, remove the constant attribute;    P1[0] = ' Z '; Cout<<p<<endl;}    int main (void) {const char buf[] = "ABCDEFG";    Programmers want to make sure that the space that P points to can be modified, if not modified, will have disastrous consequences;    const char *BUF = "abcdef";//A break error occurs because the space it points to itself cannot be modified printbuf (BUF); return 0;}

Operation Result:

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Four types of load changer in C + +