References to C + +

C + + Reference learning:

Usually the first function is quoted, and one will think of the alias of the referenced variable, which is directly manipulated.

Declaration of reference:

Type + & + name (can be considered a constant pointer)

Note: (1) & is the function of identifiers;

(2) when declaring a reference, it must first be initialized;

　　　(3) You cannot create a reference to an array because the array is composed of several elements, so you cannot create an alias for an array;

Referenced apps:

(Reference as parameter)

int swap (intint &b) {    int t = A;     = B;      =

(Reference as constant)

int Main () {  int;   Const int &a = b;   return 0 ;}

This can make the code more robust, and there are other requirements;

(Reference as return value)

Type + & + function name

(1) Return function value by reference, need to add &; in front of function name when defining function

(2) The greatest benefit of returning a function value with a reference is that it does not produce a copy of the returned value in memory.

When a function returns a stack variable, it cannot be the initial value of the other reference (because the stack variable is freed after the function ends)

int & Fun() {    return  A; When the authority variable is released, a reference to the local variable points to a memory space where it is unknown}int  main () {    int &a = Fun ();}
This is wrong.

And can not be left value;

The function returns a static or global variable: (both of these variables are placed in the global zone)

Can be used as a reference to other values, and can be left and right values;

Write a code in the following cases:

//return static variablesint&fun1 () {Static intA =1; returnA;}//return local Variablesint&fun2 () {intA =2; returnA;}//parameter is a reference to theint&AMP;FUN3 (int&a) {    returnA;}intMain () {intA =fun1 (); int&b =fun1 (); cout<<"A =" <<a << Endl; cout<<"B =" <<b << Endl;}
/* Run the result as:
A = 1;
b = 1;
*/

This is because the parameters are global;

Main () {    int a = fun2 ();     int &b  = fun2 ();} /*    The result is 2 and-2 (negative indicates pointing to memory ambiguous)* /

Because this is a local variable, when the 2nd semicolon ends, it points to an ambiguous memory area;

Main () {
int c = Ten;     int a = fun3 (c);     int &b = fun3 (c);} /*     The result of operation is    a = ten;    b = Ten; */

The reference is due to the existence of the program will not be released before the end;

References to C + +