C + + pointers explaining and places to note

int *x =&10;//cannot fetch address to 10 because he is not in the stack area//stack constant Area B can take the address of the variable

10 is a literal that can't take an address

1: Pointer is a data type

1) The pointer is also a variable, occupying memory space, used to maintain memory address, in general, all pointers,

are 4 bytes;

2) *p operating memory

When the pointer is declared, the * number indicates that the variable being declared is a pointer,

When the pointer is used, the * number represents the value of the memory space pointed to by the manipulation pointer,

*p is equivalent to finding a piece of memory through the value of the address {p variable} and then manipulating the memory

*p on the left side of the equal sign (assigning values to memory)

*p on the right side of the equal sign (Gets the value from memory)

3) A pointer variable and the memory block it points to are two different concepts;

Char s= ' a '; char *p=&s;*p= ' b ';//This operation will not change the value of the pointer variable, but will change the value of the address pointed to

Ensure that the memory pointed to is modifiable

char*p= "Abcdeff"; The C + + compiler will do two operations to give the string a memory and then assign p 4 bytes of memory

Then assign the address of a to *p, which is the first address of the string.

Char *p=null;

strcpy ([, "ABCDE"); You cannot write data to empty memory

4) How to understand (multilevel) pointers do function parameters

A. At the angle of the C + + compiler, if the parameter compiler of the pointer is only allocating four bytes of memory

For example:

/*

void sed (char *p1); void sed (char* p1)

void Send (CHAR**P1); void Send (char * * p1);

void Send (char ***p1); void send (char *p[])

void Send (char (*P) [ten]); void Send (char ******p);

*/

The maximum meaning of the pointer when two indirect assignments are present

The 1 pointer variable and the memory space he points to are different.

int a=10;

a=15; Direct Assignment

int *p=null;

*p=20; *p on the left is indirectly modifying the value of a to reflect a small meaning

But if you use the function to pass the parameter, it is different.

int Ge (INT*P)

{

*p=30;

}

int main ()

{

int a=10;

Ge (&a)

}

There's something to add next time.

C + + pointers explaining and places to note