A detailed (vi) pointer and array for the C + + language pointer usage

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1. Definition

Pointers and arrays are basically equivalent because of the way that pointers are arithmetic and how arrays are handled within C + +. --"C++primerplus" fifth edition

In most cases, C + + interprets the array name as the address of the first element in the group.

   int arr[10] = {1,2,3,4,5};   int *p = arr;   cout<< "--------------3 ways to get the address of an array-------------------" <<endl;   cout<< "Arr     " <<arr<<endl;   cout<< "&arr[0" <<&arr[0]<<endl;   cout<< "P-       ," <<p<<endl;   cout<< "--------------4 ways to get the value of an array-------------------" <<endl;   cout<< "arr[1"     <<arr[1]<<endl;   cout<< "* (arr+1),   " <<* (arr+1) <<endl;   cout<< "* (p+1),     " <<* (p+1) <<endl;   cout<< "P[1"       <<p[1]<<endl;

　

Summarize:

Arrayname[i]    equivalent to  * (arrayname+i)

2. Pointer arrays and Arrays pointers

This part of the reference Micro-blog: http://www.cnblogs.com/Romi/archive/2012/01/10/2317898.html

Pointer array: array of pointers, which is used to store pointers to arrays, which are arrays of elements that are pointers

Array pointer: A pointer to an array, which is a pointer to the array

Also note the differences in their usage, as illustrated below.

int* a[4] Pointer array

Indicates: Array a[4] is a pointer, the type of the pointer is int*, the pointer to the type is int

element means: *a[i] * (A[i]) is the same, because [] priority is higher than *

int (*a) [4] Array pointer

Indicates: A is the type of the pointer is int*[4], and the pointer is of type int () [4]

Element representation: (*A) [i]

#include <bits/stdc++.h>using namespace Std;int main () {   /***   pointer Array    * * < array pstr[3], the element of the array is the pointer >  three-province pointers: The type of the pointer is int *, the type is int, each pointer in the array points to the first address of three strings,    ***/   char *pstr[3] = {    "socialism",    "with",    "Chinese"   };   cout<< "Pstr[0"  <<pstr[0][0]<<endl;;   cout<< "pstr[1"  <<pstr[1]<<endl;;   cout<< "pstr[2"  <<pstr[2]<<endl;;   /***   Array Pointer    * * < pointer pstr1>  three-province pointer: the type of the pointer is int (*) [20], the type is int () [20], and the pointer is pointing to str1   ***/   Char STR1[20] = "characteristics";   char (*PSTR1) [] = &str1;   b=&str1;   cout<< "*pstr1   " <<*PSTR1<<ENDL;;}

　

Note: The string is equivalent to an array constant, the contents are immutable and can only be rvalue, and if viewed as pointers, constant pointers are also pointer constants

Pointer constant: The pointer is a constant, immutable, point to an address can not be changed, but 0 points to the cell is able to change, the general reading constant point

Constant pointer: The value of a pointer cannot be changed, but itself is a variable, which is read as a pointer to a constant

3. Summary of the first address of the array

Array name is the first address of an array

a) Meaning:

Declares an array: TYPE arrayname[n];

There are two layers of meaning: 1.arrayname is an array, the type is type[n]

2.array is a constant pointer, the type of the pointer is type *, the point is type, the value pointed to is the No. 0 element of the array, note that the address of arrayname and the No. 0 element of the group is different, arrayname is a pointer constant, arrayname++ Is wrong.

b) function

sizeof (Arrayname)	Arrayname represents the array itself, resulting in the size of the entire array
*arrayname (equivalent to arrayname[0])	Arrayname represents the pointer, and the value of the No. 0 element of the array is obtained.
Arrayname+i	Arrayname represents a pointer to a pointer that is shifted backwards from I to a unit of type

Add: sizeof (object) is measured by the type size of the object itself

A detailed (vi) pointer and array for the C + + language pointer usage