Category:C: Difference between revisions

===Types===

C has the following types built in by default, but you can create your own based on these using the <code>typedef</code> directive.

* char: an 8 bit value, typically used to represent ASCII characters.

* short: a 16 bit value.

* int: a 32 bit value.

You can also add a few modifiers in front of the variable type to be more specific:

* <code>unsigned</code> tells the compiler that this variable is always treated as positive. Computers use two's complement to represent negative numbers, meaning that if the leftmost bit of a number's binary equivalent is set, the value is considered negative. The resulting assembly code will use unsigned comparisons to check this variable against other variables.

* <code>volatile</code> tells the compiler that this variable's value can changed by the hardware. This is commonly used for hardware registers such as those that track the mouse cursor's location, a scanline counter, etc. The value will always be read from its original memory location, ensuring that its value is always up-to-date.

Examples:

<lang C>unsigned int x;

volatile int HorizontalScroll;</lang>