Pointers

Pointers are variables that store memory addresses
- Typically of other variables

This is useful for directly modifying a variable outside of your scope

PATH: "https://raw.githubusercontent.com/ThomasCarey4/COMP1711/main/pointers.c"
TITLE: "Example 1"

This code will directly modify the 'num' variable from inside the test function, without returning it or creating a copy.

This is useful because, for example, if 'num' was a really large data type (such as a massive array) you can modify it inside functions without taking the time to create a local copy of the variable.

• This allows for significant increases in spatial and temporal efficiency

Syntax

&num // = The address of 'num'
*add // = The value stored at address 'add'
*&num // = The value at the address of 'num' = 'num'
%p // = The format specifier for a memory address

Pointer Arithmetic

PATH: "https://raw.githubusercontent.com/ThomasCarey4/COMP1711/main/pointer-arithmetic.c"
TITLE: "Example 2"

The Definition of an Array

The reason this works is because in C arrays are defined by:

x[y]
// Where x = Pointer to the first item
// and y = how many steps after

In the 'Example 2', the variable 'array' is effectively a pointer to 'array[0]'
When you call 'array[1]' the program first points to 'array[0]' and then steps to next memory address, which would be 'array[1]'

Syntax

*add++ // = Access the address, then add 1
*++add // = Add 1 to the address, then access it