Editing Pointer (computer programming) (section)

===Memory-mapped hardware===
On some computing architectures, pointers can be used to directly manipulate memory or memory-mapped devices.

Assigning addresses to pointers is an invaluable tool when programming [[microcontroller]]s. Below is a simple example declaring a pointer of type int and initialising it to a [[hexadecimal]] address in this example the constant 0x7FFF:

<syntaxhighlight lang="C">
int *hardware_address = (int *)0x7FFF;
</syntaxhighlight>

In the mid 80s, using the [[BIOS]] to access the video capabilities of PCs was slow. Applications that were display-intensive typically used to access [[Color Graphics Adapter|CGA]] video memory directly by casting the [[hexadecimal]] constant 0xB8000 to a pointer to an array of 80 unsigned 16-bit int values. Each value consisted of an [[ASCII]] code in the low byte, and a colour in the high byte. Thus, to put the letter 'A' at row 5, column 2 in bright white on blue, one would write code like the following:

<syntaxhighlight lang="C">
#define VID ((unsigned short (*)[80])0xB8000)

void foo(void) {
    VID[4][1] = 0x1F00 | 'A';
}
</syntaxhighlight>