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 &)
& Get the address character
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
}
* 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
Cout
}

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
Cout
Cout
Cout
Cout
Cout
// 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
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
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