Differences between C ++ pointers and references

Today, we can see the C ++ pointer. By the way, let's look at the difference between the pointer and the reference ..

1. First, the reference must be initialized, And the pointer does not have. So if you use a variable and point it to an object, but the variable may not point to any object at some time, this should be declared as a pointer; on the contrary, if you confirm that the variables used are not allowed to be null at any time during design, you should declare the variables as references. Because the reference does not point to a null valueCodeEfficiency is higher than pointer.

String & S; // error. The reference must be initialized.

String STR = "123456 ";

String & s = STR; // point S to the STR variable

2. Difference in legitimacy: you do not need to test its legitimacy before using the reference, but the pointer is always tested to prevent it from being empty.

3. Modification difference: the reference cannot be modified after initialization, And the pointer can modify the object to which it points.

4. Application: the pointer should be used in the following situations:

(1) When there may be variables that do not point to any object, Use Pointer variables.

(2) Use Pointer variables when pointing to different objects at different times.