C ++ reference concept

C ++ reference concept

That is a reference map to another variable, or that is an alias for another variable, the variable name with a reference name and variable content can be accessed

definition

int num = 10;
int &r = num;   // 创建了引用r

printf("%d\n", num);    // 10
printf("%d\n", r);      // 10

Unlike pointers

• After the reference must be initialized when they are declared, this is a bit like a constant pointer can be declared no longer be assigned
• Reference can not replace the referenced object, you can only reference a variable from the beginning of creation, and a pointer to an object can be replaced
• Null reference does not exist, it must refer to a valid memory address, and the pointer can be null pointer

Const reference

Typically reference refers only to the same type of values ​​and their

int num = 10;
int &a = num;   // 引用a只能引用int型的对象

But by the constmodified reference different, and it can refer to different types of self-reference (the premise is that the system can convert over type), or even a literal reference

int &a = 120;   // 错误
const int &a = 120; // 正确