regex capital letter only of a string

[ggalan]

i saw that from a previous post, this works to filter out only the numbers

$string = "this is a STring123 test";
$numbers = preg_replace('/.*?(\d+).*/', '$1', $string);
echo $numbers; 

but how can i modify that regex to filter out only the capital or lowercase ?

[ggalan]

actually i found that this will out put the last 3 digits of a string

$str = "My string";
echo substr($str, -3); 

anyone know how to get the first 2 digits?

[ggalan]

nm

echo substr($str, 0, 2); 

[james438]

are you still needing help or did you find what you are looking for? from what I am reading I am not sure what exactly it is your script is being used for.

[ggalan]

originally i wanted a script / regex to pull only the upper or lower case of a string