Re^2: Using a Regexp to match a string exactly

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Re^3: Using a Regexp to match a string exactly by bart (Canon) on Jan 28, 2010 at 06:23 UTC
Not just `eq`/`ne`... but any expression that returns a true or false value — which implies: any expression in scalar context. (`undef`, `""` and 0 are false, anything else is true.) The generic variable `$_` holds the value of the current item from the list. Actually, it's even stronger than that: `$_` is an alias to the current item, which means: same value (by reference; you could say: same variable); different name. If you modify `$_` in that expression, the original value will have changed. Example: `@original= (0 .. 5); @true = grep $_*=2, @original; local $" = ", "; # for nicely formatted output print "original: @original\n"; print "output: @true\n";` [download] Result: `original: 0, 2, 4, 6, 8, 10 output: 2, 4, 6, 8, 10` [download] Each item in the original array has been doubled. Of those, only the nonzero (true) values have been come through the `grep` filter.	[reply] [d/l] [select]

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Re^3: Using a Regexp to match a string exactly
by bart (Canon) on Jan 28, 2010 at 06:23 UTC

eq

ne

any

undef

""

The generic variable $_ holds the value of the current item from the list. Actually, it's even stronger than that: $_ is an alias to the current item, which means: same value (by reference; you could say: same variable); different name. If you modify $_ in that expression, the original value will have changed. Example:

@original= (0 .. 5);
@true = grep $_*=2, @original;
local $" = ", ";  # for nicely formatted output
print "original: @original\n";
print "output: @true\n";
[download]

original: 0, 2, 4, 6, 8, 10
output: 2, 4, 6, 8, 10
[download]

Each item in the original array has been doubled. Of those, only the nonzero (true) values have been come through the grep filter.

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