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Re: how many lines returned from backticks

by dws (Chancellor)
on Jun 30, 2002 at 03:56 UTC ( #178303=note: print w/replies, xml ) Need Help??

in reply to how many lines returned from backticks

If the program returned 5 lines the first time, and only 2 the next, won't there be lines left over from the first time? How can I tell how many _additional_ lines I got back?

This rather depends on how you have things scoped. If the backticks are in a subroutine that gets called multiple times, each invocation of the routine will get a new array if the backticks line is coded as:   my @lines = `findgsc ...`;
If you move the declaration of @lines higher in the script, and then do   @lines = `findgsc ...`;
multiple times, each one overwrites @lines with new values. To get a delta on line count (i.e., note additional lines), merely save the prior count. Conceptually,

@lines = `finedgsc ...`; $prevLines = scalar @lines; @lines = `findgsc ...`; if ( scalar @lines > $prevLines ) { # we got more this time }
Note that scalar @lines is the absolute line count, while $#lines is the final index in the array, which will be one less than the absolute count. Which to use is a matter of style, but don't confuse the two.

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