What is a pointer? What is an array? Pointer and array relationships?

What is a pointer? What is an array? Pointer and array relationships?

Figuratively speaking, we can think of the computer's memory as a row of houses on a long street, where each room can accommodate data and be identified by a room number. And the value of each room number we can call the address. Perhaps this analogy has limitations, after all, real computer memory is composed of tens of thousands of bits.

⑴ initialization:

① is the simplest example of an int *p, which opens up four bytes of space in memory during initialization.

▇▇▇▇

② Another statement, now we have two variables that show the memory of the unknown content in the back.

char ch = ' a ';

char CP = &a;

▇→▇▓← (? )

(CP) (CH)

⑵ use of "*"

① defines the pointer variable is

② a section reference to a pointer variable is

★ NOTE 1: To implement the move of the address, it is p++, not *p++

★ NOTE 2:

int *p = NULL; Represents the creation of a pointer variable and initializes it.

*p = null;//Change the contents of the access to null.

★ Note 3: What is the difference between an array int a[4],&a and a? The &a is the same as the content of a, but the &a+1 adds 16 bytes, and A+1 adds a byte. The reason is that &a is the address of the entire array, and a is the address of the first element of the array.

The table below gives us a deep understanding of the difference between pointers and arrays

a[]={1,2,3,4}	Char name[]= "abcdef"	Char *name= "abcdef"
sizeof (a) =16	sizeof (Name[0]) =1	sizeof (&name) =4
sizeof (&A) =16	sizeof (&name) =4	sizeof (*name) =1
sizeof (A+0) =4	sizeof (*name) =1	sizeof (&NAME+1) =4
=4sizeof (*a) =4	sizeof (&NAME+1) =4	sizeof (name) =4
sizeof (A+1) =4	sizeof (NAME+1) =4	sizeof (NAME+1) =4
sizeof (&A) =4	sizeof (name) =7	strlen (name) =6
sizeof (&a[0]) =4	Strlen (&name) =6	Strlen (&name) =6
sizeof (&A[0]+1) =4	Strlen (&name+1) =12	strlen (&name+1) = random value

The difference between a pointer array and an array pointer

Array of pointers: arrays that store pointers, that is, array elements are pointers.

Array pointer: A pointer to an array.

An expression	Type	Said	Element representation
int a[4]	Array of integral type	Integer array with 4 elements	A[i]
int *a[4]	Array pointers	The element in a is an int type pointer	*a[i] or * (A[i])
int (*a) [4]	Array pointers	Pointer to array a	(*a) I

▲int *: Access four bytes at a time.

▲char *: One-time access to a byte.

What is a pointer? What is an array? Pointer and array relationships?