regex - Regexp for a +ve (or -ve) fraction number in Tcl -

i trying figure out regexp expression getting

40 in
optical power = 40 dbm

and -5.5 in
optical power = -5.5 dbm

i used (\+|-?[0-9]+\.[0-9]+). wont work first case.

you may try this,

[+-]?[0-9]+(?:\.[0-9]+)? 

[+-]? matches optional plus or minus character.