C + + Tutorial local variable, reference, constructor after Colon

The following syntax is encountered, after which the variable is assigned a value

class a{
int a;
int b;
 public :       int int bb): a (aa), b (bb)    {    }}

Equivalent to:

int int Bb) {a=aa;b=bb;}

Code location:

#include <iostream>using namespacestd;classa{ public: A (intMsg) {                 this->msg =msg; cout<<"Create a\n"; }        ~A () {cout<<"Destroy A\n"; }        intmsg;};voidSwap (a& A, a&B) {A Temp=a; A=b; b=temp;}intmain () {a A (1); A B (2); Std::cout<<"a="<<a.msg<<"b="<<b.msg;        Swap (a, b); Std::cout<<"a="<<a.msg<<"b="<<b.msg; Std::cout<<"Hellow world"; //will A be destroyed?         return 0;}

1 Local variable creation

Create objects on the stack directly within a scope a (corresponding parameterless Constructor) and a a (1) (with parametric constructors)

2 References to issues

C's function if not with a reference is passed by value! The following function

void Swap (* a, A * b) {        a* temp = a        ; = b;         = temp;}

It is useless to write a swap object like This.

Since the pointer is a value passed, the Swap function is left as usual

　　

C + + Tutorial local variable, reference, constructor after Colon