INT A = 1;
INT * b = & a;
INT ** C = & B;
Printf ("& a:% d \ n", & a);
Printf ("B:% D \ N", B);
Printf ("& b:% d \ n", & b);
Printf ("* b:% d \ n", * b);
Printf ("** c:% d \ n", ** c);
Printf ("* c:% d \ n", * c);
Printf ("C:% D \ N", C);
Printf ("& C:% D \ N", & C);
operation result:
Use the VS2010 with VS2010 under Windows:
& a = b = * c = is address
A = * b = ** c = 1 is a value
& b = c is address
& c is address
When you declare, you can't have two heads.
First-level pointer B corresponds to one level pointer & a
Secondary pointer C corresponds to secondary pointers & b
Pointer to correspond to the level!
Aggregate string
Char * a = "abc";
Char * b = a;
Printf ("a:% s \ n", a);
Printf ("B:% S \ N", B);
Output:
A: ABC
B: ABC
See a program understanding address
Char * p = "a";
Char * p1 = p;
INT A = 1;
INT * b = & a;
Printf ("p:% s \ n", p);
Printf ("* p:% d \ n", * p);
Printf ("& P:% D \ N", & P);
Printf ("& P [0]:% D \ N", & P [0]);
Printf ("P1:% S \ N", P1);
Printf ("* p1:% d \ n", * p1);
Printf ("& P1:% D \ N", & P1);
Printf ("& P1 [0]:% D \ N", & P1 [0]);
Printf ("* b:% d \ n", * b);
Printf ("B:% D \ N", B);
Printf ("& a:% d \ n", & a);
Printf ("& b:% d \ n", & b);
Note: When the pointer points to the string pointer, it will not bring *, and the pointer is a value of the value pointer & address.
Char * menu [] = {
"ABC",
"DEF",
"MNP",
NULL,
}
Main ()
{
CHAR ** OPT;
Opt = menu;
Printf ("% d \ n", OPT);
Printf ("% s \ n", * OPT);
}
Output:
134518260ABC
Pointer role
Use only pointer
SWAP (int * a, int * b)
{
INT C = 0;
C = * a;
* a = * b;
* b = C;
}
int main ()
{
INT A = 1;
INT C = 2;
INT * B = & C;
SWAP (& A, B);
Printf ("a:% d \ n", a);
Printf ("B:% D \ n", * b);
Return 0;
}
Pointer using a pointer
SWAP (int * a, int ** b)
{
INT C = 0; c = * a;
* a = ** b;
** b = C;
}
int main ()
{
INT A = 1;
INT C = 2;
INT * B = & C;
SWAP (& A, & B);
Printf ("a:% d \ n", a);
Printf ("B:% D \ n", * b);
Return 0;
}
Passing the address of the pointer to the pointer of the pointer, the function is called!
Not a function call, directly assign a value.
