Array pointer and function pointer

Pointer array, array pointer, function pointer:

1. pointer array: the data items of the array are pointers. The most common is the string pointer array. See the following example:

Char * cities = {"Jinan", "Qingdao", "biejing", "Shanghai", "Wulumuqi "};

Note the initialization method of pointer array: Put the five string constants in the Data zone, and cities only store these five pointers.

Comparison with 2D data:

Char cities2 [] [9] = {"Jinan", "Qingdao", "biejing", "Shanghai", "Wulumuqi "};

This looks very similar to the pointer array. The occupied space is quite different: the pointer array contains actual space, and each string in the two-dimensional array occupies nine characters.

2. array pointer: pointer to an array. This can distinguish between function pointers and pointer arrays. For example:

INT (* pint) [5]; // array pointer

INT (* pfunc) (INT); // function pointer ----------- is similar in shape? Is the name very similar?

Array pointer type (data type): int (*) [5], the following code will give an error prompt:

Int A [5] = {1, 2, 3, 4, 5 };

Pint = A; // error message: Type incompatible int (*) [5] to int *

Pint = & A; // correct, reflecting the concept of pointing;

Generally, array pointers and two-dimensional arrays are used together:

Int AA [3] [5] = };

Pint = AA;

3. function pointer: pointer to a function.

Its Type: int (* pfunc) (INT); ---> int (*) (INT)

Function pointers are mainly used as the address for passing function parameters. But it can also be used as the return value.

Parameter: int signal (INT Sig, void (* func) (INT ))

Return Value: void (* signal2 (INT). signal2 parameter is int, return value is void (*) (INT)