PHP global variables

Question

Why does the following result in an error message? (it is declared inside a function in PHP by the way; $a and $b are alphabetic values, not numeric)

global $pre[''.$a.''], $predis[''.$b.''];

Parse error: syntax error, unexpected '[', expecting ',' or ';' in ...

Answer 1

global $pre, $predis;

Then use $pre and $predis how you want.