reg exp help

[Jim]

Hi,

I'm trying to make a regular expression for the following:

I am creating a message format as follows:
start of string has the length of a message
'E' character indicates end of the length part
the rest of the string is the true message, example:

"5Ehello"

I need a reg exp that will return for me the length, and also the msg
portion (in this case 'hello' ) only if the length is correct (5 in
this case).

Any help is appreciated, thank you.