Array-pointer-Reference

I. pointer Concept

The pointer is the address in the memory.

1. Syntax: type * variable name
The type here defines the variable type pointed to by this pointer.

2. pointer operators (* and &)
<1> & get the address Operator
For example:
Int counta = 100;
Int * mm;
Mm = & counta;
Assume that the counta address is 2000, which is waiting for m = 2000.
# Include
Void main ()
{
Int counta = 100;
Int * mm;
Mm = & counta;
Cout < }
<2> * return the value of this address, which is opposite.
# Include
Void main ()
{
Int p, counta = 100;
Int * mm;
Mm = & counta;
P = * mm;
Cout < }
3. pointer assignment

# Include
Void main ()
{
Int x;
Int * p1, * p2;
P1 = & x;
P2 = p1;
Cout < }

Result: 0x0012FF7C.
4. pointer operation
The ++ and -- of the pointer move the pointer address to the number of digits of the variable type.

Char 8
Int 16
Long 32
Float 32
Double 64
5. pointers and Arrays

Array declaration: type variable name [length]

The "one-dimensional" array name without the following mark is a pointer to the first element of the array.

# Include
Void main ()
{
Int x [3] = {1, 2, 3 };
Int * p1;
P1 = x;
Cout < }
A. equivalence relationship:

For example, char c [10];
C and & c [0] are equivalent.

For example, char c [2] [3];
C and & c [0] [0] are equivalent.
* (C + 12) and & c [1] [2] are equivalent.

B. Relationship between arrays and pointers

1> pointer to one-dimensional array

# Include
Void main ()
{
Int x [2] = {1, 2 };
Int * p1;
P1 = x;
Cout <* p1 <"\ n ";
Cout <* (p1 + 1) <"\ n ";
}

2> two-dimensional array pointer

# Include
Void main ()
{
Int
X [2] [3] = {1, 2, 4, 5, 6 };
// Int x [2] = {1, 2 };
Int * p1;
P1 = & x [0] [0]; // For a two-dimensional array, the pointer cannot be assigned with the value "p1 = x". It can only be "p1 = x [2]".
Cout < Cout < Cout < Cout < Cout < Cout < 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 ))
}

Think: if the pointer is an address, how can I get the variable of an address.

2. Compare references with pointers

A reference is the alias of a variable.

# Include
Void main ()
{
Int x p1, a = 100;
Int & y1 = a; // values must be assigned directly.
P1 = &;
Y1 =;
Cout <* p1 <"\ n ";
Cout < }

Pointers and references can achieve the same effect.

# Include
Void main ()
{
Void funca (int & vala );
Void funcp (int * valp );
Int a = 100, B = 100;
Int & y1 = a; // values must be assigned only once.
Funca ();
Funcp (& B );
Cout < }
Void funca (int & vala)
{
Vala = 200;
}
Void funcp (int * valp)
{
* Valp = 500;
}

3. Use and to avoid obfuscation of these symbols.

1. * functions:

1> multiplication number
2> pointer definition symbol
3> return the value of an address.

2. & role:

1> "and" In bitwise operations"
2> get the address character
3> reference

This article is from the "pure" Programmer Club "blog. For more information, contact the author!