NXC Version 1.2.1 r5
The void keyword allows you to define a function that returns no data.
Functions that do not return any value are sometimes referred to as procedures or subroutines. The sub keyword is an alias for void. Both of these keywords can only be used when declaring or defining a function. Unlike C you cannot use void when declaring a variable type.
In NQC the void keyword was used to declare inline functions that could have arguments but could not return a value. In NXC void functions are not automatically inline as they were in NQC. To make a function inline you have to use the inline keyword prior to the function return type as described in the Functions section above.