First, the concept of pointer
The pointer is the address in memory.
1, grammar: Type * variable name
The type here is defined the type of variable points to this pointer.
2, the operator of the pointer (* and &)
<1> & Take Address
E.g:
INT counta = 100;
INT * mm;
MM = & counta;
Suppose the address of Counta is 2000, this is M = 2000.
#include
void main ()
{
INT counta = 100;
INT * mm;
MM = & counta;
Cout <
<< "/ n";
}
<2> * Returns the value of this address, opposite to & just.
#include
void main ()
{
INT P, counta = 100;
INT * mm;
MM = & counta;
P = * mm;
Cout <
<< "/ n";} 3, the assignment of pointer #include
void main ()
{
INT X;
INT * P1, * P2;
P1 = & x;
P2 = P1;
Cout <
<< "/ n";
}
Results: 0x0012FF7C
4, pointer operation
Pointer and - is the number of variable type digits to move the address of the pointer.
Char 8
INT 16
Long 32
Float 32
Double 64
5, pointer and array
Array declaration: Type variable name [length]
The "one-dimensional" array name without the subscript is a pointer to the first element of the array.
#include
void main ()
{
INT x [3] = {1, 2, 3};
INT * P1;
P1 = x;
Cout <
<< "/ n";
}
a, equivalent relationship:
Such as: CHAR C [10];
C and & C [0] are equivalent.
Another example: char C [2] [3];
C and & C [0] [0] are equivalent.
* (C 12) and & C [1] [2] are equivalent.
b, array and pointer relationship
1> Pointer in one-dimensional array
#include
void main ()
{
INT x [2] = {1, 2};
INT * P1;
P1 = x;
Cout << * p1 << "/ n";
COUT << * (p1 1) << "/ n";
}
2> 2D array pointer
#include
void main ()
{
int
x [2] [3] = {1, 2, 3, 4, 5, 6};
// int x [2] = {1, 2};
INT * P1;
P1 = & x [0] [0]; // The two-dimensional array gives the pointer to assign a value with "P1 = X", can only be "p1 = x [2]"
Cout <
<< "/ n";
Cout <
<< "/ n";
Cout <
<< "/ n";
Cout <
<< "/ n";
Cout <
<< "/ n";
Cout <
<< "/ n";
Cout << * p1 << "/ n";
COUT << * (p1 1) << "/ n";
COUT << * (P1 2) << "/ n"; cout << * (p1 3) << "/ n";
COUT << * (P1 4) << "/ n";
COUT << * (P1 5) << "/ n";
// rule: * (p1 ((1 * 3) 2))))
}
Thinking: The pointer is the address, then what method is used if you want to get a variable of an address.
Second, compare references and pointers
Quote is the alias of the variable.
#include
void main ()
{
INT * P1, A = 100;
INT & Y1 = a; / / must be directly assigned
P1 = & a;
Y1 = a;
Cout << * p1 << "/ n";
Cout <
<< "/ n";
}
The pointer and reference can achieve the same effect.
#include
void main ()
{
Void Funca (INT & VALA);
Void Funcp (INT * VALP);
INT A = 100, b = 100;
INT & Y1 = a; / / must be directly assigned, and can only be assigned once
FUNCA (A);
Funcp (& B);
Cout <
<< "/ n"; cout <<< "/ n";} void funca {var = 200;} void funcp (int * valp) {* VALP = 500;} 3, * and & Uses, avoid these symbols in use, the effects of confusion 1, *: 1> Multiplier 2> Pointer definition symbol 3> Return to a value of an address 2, & effect: 1> "and" 2 " Take Address 1> Reference
