[SOLVED] PHP function with parameter

I need to use a PHP function. ( I have never used a PHP function. )
First call of function will be with parameter Array containing 49 string elements;
Second call of function will be with parameter Array containing 35 string elements;
May be in the future will use function with parameter Array containing ## string elements;

Help about declaration and usage of that kind of function will be great.

function myfun($par1) {
...
}

$par1= array('str1', ..., 'str39');
myfun($par1);