See the responses to Script to list out the functions of a C file, you're not the first person to ask this type of question (Super Search is your friend). Please don't ignore the post formatting advice displayed. Read and understand PerlMonks for the Absolute Beginner and How do I post a question effectively?.
Update: As you're new to perl the following will help:
In reply to Re: Identifying functions in a c file and replacing with a keyword
by marto
in thread Identifying functions in a c file and replacing with a keyword
by ijalab
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