Conditional Operator
Ternary "?:" is the conditional operator, just as in C. It works much like an if-then-else. If the argument before the ? is true, the argument before the : is returned, otherwise the argument after the : is returned. For example:
1 2 | printf "I have %d dog%s.\n", $n,($n == 1) ? "" : "s"; |
Scalar or list context propagates downward into the 2nd or 3rd argument, whichever is selected.
1 2 3 | $x = $ok ? $y : $z; # get a scalar@x = $ok ? @y : @z; # get an array$x = $ok ? @y : @z; # oops, that's just a count! |
The operator may be assigned to if both the 2nd and 3rd arguments are legal lvalues (meaning that you can assign to them):
1 | ($x_or_y ? $x : $y) = $z; |
Because this operator produces an assignable result, using assignments without parentheses will get you in trouble. For example, this:
1 | $x % 2 ? $x += 10 : $x += 2 |
Really means this:
1 | (($x % 2) ? ($x += 10) : $x) += 2 |
Rather than this:
1 | ($x % 2) ? ($x += 10) : ($x += 2) |
That should probably be written more simply as:
1 | $x += ($x % 2) ? 10 : 2; |
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