Pointers - C - C++

All information shamelessy copied from

https://c-for-dummies.com/caio/pointer-cheatsheet.php
        

Pointer Pointers

A pointer must always be of the same type as the variable it's pointing at.
Declaring a pointer variable does not create the type of variable it points at. It creates a pointer variable.
Though pointers are declared with an asterisk they are not always used with an asterisk.
The asterisk is the unary * operator. It is not the * multiplication operator.
Pointers must be initialized before they can be used.
Initialize a pointer by assigning it to a variable; the variable must be of the same type as the pointer.
To assign a pointer to a variable, use an ampersand with the variable's name.
The address-of unary operator & is not the same as the bitwise & AND operator.


m_address = &memory;

To assign a pointer to an array, do not use the ampersand:
s_address = string;

The pointer s_address would be used on the string array's elements.

To assign a pointer to an array element, use the ampersand:
element = &string[2];

Without an asterisk, an initialized pointer holds a memory address.
With an asterisk, an initialized pointer references the value stored at its address.
        

Typical Pointer Setup and Use

First, create a pointer of the proper type:

float *f;

Second assign it to a variable's memory location:

f = &boat;

Finally, use the pointer:

printf("%.0f",*f);
        

Pointers, Parenthesis, and Math

Pointer Thing	Memory Address	Memory Contents
p	Yep	Nope
*p	Nope	Yep
*p++	Incremented after value is read	Unchanged
*(p++)	Incremented after value is read	Unchanged
(*p)++	Unchanged	Incremented after it's used
*++p	Incremented before value is read	Unchanged
*(++p)	Incremented before value is read	Unchanged
++*p	Unchanged	Incremented before it's used
++(*p)	Unchanged	Incremented before it's used
p*++	Not a pointer	Not a pointer
p++*	Not a pointer	Not a pointer

Pointers and Array Brackets

Array Notation	Pointer Equivalent
array[0]	*a
array[1]	*(a+1)
array[2]	*(a+2)
array[3]	*(a+3)
array[x]	*(a+x)

Ugly ** Notation

Doodad	What It Is	Seen by The Compiler
array+1	An address	A pointer
*(array+1)	Contents of address, what lives there	A string
*(*(array+1))	Contents of a character array	A character
**(array+1)	Same as above	Same as above