regex pattern not fit well for code like assignment

Question

i am trying to use a regular expression to match expression like code assignment for example:

"k=++g677"
"k=--j77"
"k=++gfrf677frfr"

i've tried:

([a-zA-Z])([a-zA-Z]|\d)*[=][+][+]|[-][-]|[*][*]|[\/][\/]([\d]*|([a-zA-Z]([a-zA-Z]\d)*))

but it's seemds to match also things like

"k++"
"k=++@ff"

can u help?

Answer 1

You may use

^[a-zA-Z_][\da-zA-Z_]*=([+*\/-])\1[a-zA-Z_][\da-zA-Z_]*$

Or, if you need to capture each detail into a separate group:

^([a-zA-Z_][\da-zA-Z_]*)(=)(([+*\/-])\4)([a-zA-Z_][\da-zA-Z_]*)$

See this regex demo and its graph:

Details

• ^ - start of string
• [a-zA-Z_] - an uppercase ASCII letter or underscore
• [a-zA-Z\d_]* - 0 or more alphanumerics / _ (replace with \w if it is not Unicode aware by default)
• = - an equal sign
• ([+*\/-])\1 - +, *, / or - and then exactly 1 the same char
• [a-zA-Z_] - an ASCII letter or _
• [a-zA-Z\d_]* - 0 or more alphanumerics / _ (replace with \w if it is not Unicode aware by default)
• $ - end of string.