C + + Basics Tutorial-pointers

The use of pointers can directly manipulate the memory address, improve efficiency, the disadvantage is detours more difficult to understand, this tutorial for you to introduce the pointers in C + + language.

1, start Geany

1 point Menu "application-programming-geany" Start Geany, create a new C + + source program;

2 Point Menu "file-Save as" command, to "PTR" as the filename, save the file to its own folder;

2. Pointer variable

1 Use the pointer before you also define, with the * number to define, assignment with the address of other variables, can also be initialized to null;

Enter the following code:

int a = 25;

int *p = NULL;

p = &a;

2 The first sentence defines an integer variable A, each variable has a memory address, with the &a command to get the address of the variable,

The second sentence defines a pointer variable, the type is integral, the asterisk * is the definition symbol, and Null indicates that the assignment is null.

The third sentence is to assign a value to the pointer variable p, the value is the address of the variable A, formatted like 0x123456;

3) Then we will show the values of each variable, corresponding to their respective types;

cout << "a =" << A;

cout << "&a=" << &a;

cout << "p =" << p;

4 A is an integer variable, which is filled with integers, &a is the address operator, and gets the address,

P is a pointer variable, which holds the address, p gives the address of a, so two addresses are the same;

5 Next we look at using the pointer to manipulate its corresponding variable, continue to enter the following code;

cout << "*p=" << *p << Endl;

6 The *p here is not a definition pointer, because the asterisk * has no type before, and P has been defined and cannot be defined repeatedly,

The *p here is an indirect reference, pointing to A, because P holds the address of a, so the *p value is 25;

7 using *P can operate on variable A, for example, the following code assigns a value to A;

*p = 16;

cout << "a =" << A;

#include <iostream>

using namespace Std;

int main (int argc, char** argv)

{

int a = 25;

int *p = NULL; Defines the pointer variable and initializes the

p = &a; assigning to pointer variables

cout << "a =" << a << Endl;

cout << "&a=" << &a << Endl;

cout << "p =" << p << Endl;

cout << Endl;

cout << "*p=" << *p << Endl;

cout << Endl;

*p = 16; Indirect references, not defining pointers

cout << "a =" << A;

return 0;

}