From hjiwa@gruc19.nor.chevron.com (Jeff Wang)
Subject: Re: nth occurance of a string
Date: 9 Jun 93 17:27:41 GMT

gaspar@angelo.amd.com (Harand Gaspar) writes:
|>   How does one find the nth occurance of a string or regualr expression
|> in a file using vi?

Try this keymap :-) 

"? v         - Find the nth occurrence of the pattern on the current line.
"?               Enter pattern to search (can use regular expressions) on a new
"?               line, then enter number (>1 but no more than 60 occurrences)
"?               followed by \f in command mode to look for the pattern's nth
"?               occurrence.  nowrapscan must be set.  If a mistake was made in
"?               the pattern that was requested, u undo to bring back pattern.
map v I@x^[a^M^M/^[:mo---^M"xddf@imz`add`z^["yddma@yk

where ^[ are quoted <Escape> keys and ^M are quoted <Return> keys.

   Pressing the mapped key <v> (or whatever you map it to) will find the nth
occurrence of the pattern on the current line.  For example, if you want to go
the 30 occurrence of the pattern "Due Date", enter "Due Date" on a new line.
Then, press <3> <0> <v> without pausing.  The pattern will be deleted and you
will be brought down to the 30th occurrence of "Due Date", if it exists.  If you
press <u> to undo at this point, you will be returned back up to the pattern,
where you may make changes if desired.  Note that the counting of the number of
occurrences begins at the point after the pattern is typed, not from the first
line in the file.  To find nth occurrence from the start of the file, enter the
pattern on line 1.  The keymap has a limit of finding up to the 60th occurrence
of a pattern on the version of vi I am using before it chokes with the error
message "Register too long to fit in memory".  Your vi might allow more; if your
vi also has this limit and you need to count more finds (say...the 200th
occurrence), you could first find the 60th and then open up a new line, type the
pattern again on the new line, and execute the keymap again to bring you down to
the 120th occurrence, etc, etc.  You must also "set nowrapscan" or else the
keymap will wrap around the end of file and keep counting.  If you enter a
number that is greater than the actual number of occurrences, the keymap will
bring you down to the last pattern that it found, but you will see the usual
"Address search hit BOTTOM without matching pattern".
   Regular expressions can also be used.  If you type "[Th]he   /" on a new
line, it will find and count all occurrences of "The" or "the" only if the
word is followed by 3 spaces.  If you type \<[Dd]ate\> on the line and then
enter <4><5><v>, it will find the 45th occurrence of "Date" or "date" (only if
it is an entire word), and skip past "dated", "Dates", etc.   Basically, any
valid vi search string can be used; the keymap just slaps a "/" in front of it
and executes the find command "n" number of times.

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>> Jeff Wang                             Net   : hjiwa@gruc19.