原创 Array And Pointer In C Language

Array Definition In C Language:   

        One demension definition cast,            DataType ArrayName[Size];

       Two demension definition cast,            DataType ArrayName[SizeX][SizeY];  

       Instantation only definition without initialization      

       int a[10];//define a one-demesion array which is composed of ten integer sequence.

       char b[3][4];//define a  two-demesion charactor array(column size is 3 and row size is 4).     

       //initialization here

       Instantation   initialization while definition

       int a[10] = {1, 2, 3, 4};//innitial the first four integer elements, compiler specify the others numerical zero

       char b[3][4] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};//innitial the whole arrary

       Caution: when refer the element, the subscript grows begins 0, 1,  2, ... , size-1. a[0] is the first

       element's content.  

Pointer Definition In C Language          Signification

       DataType*  PointerVariable;               Point to a address of DataType variable

       DataType*  PointerVariable[Size];      A pointer array in which all element point to address of DataType

       (DataType*  PointerVariable)[Size];    Point to consecutive size length memory  of DataType          

       DataType**  PointerVariable;              Point to Pointer Variable

       Instantation (note a and b symbol refers in array definition above)

       int* p1 = a;//p point to the first element of array, symbal 'a' represent the first element address of  array

       (int* p2)[10] = &a; //p point to a consecutive ten integer variable memory address,'&a' is the header 

                   pointer of this array and its value is equal to 'a',but  meaning is differece from 'a'.

       (int* p3)[4] = b;// p point to the first row header of 'b' matrix, b herein represent &b[0].

       int* p4[3] = {&b[0][0], &b[1][0], &b[2][0]};//define a pointer type array, the memory contains the header

                                                                      of  3  rows  respectively.  

       int **p5 =  &p1;  // pointer p5 point to pointer variable p1