ЭЛЕКТРОННАЯ БИБЛИОТЕКА КОАПП |
Сборники Художественной, Технической, Справочной, Английской, Нормативной, Исторической, и др. литературы. |
1.3. Exchanging Values Without Using Temporary VariablesProblemYou want to exchange the values of two scalar variables, but don't want to use a temporary variable. DiscussionMost programming languages force you to use an intermediate step when swapping two variables' values: $temp = $a; $a = $b; $b = $temp; Not so in Perl. It tracks both sides of the assignment, guaranteeing that you don't accidentally clobber any of your values. This lets you eliminate the temporary variable: $a = "alpha"; $b = "omega"; ($a, $b) = ($b, $a); # the first shall be last -- and versa vice You can even exchange more than two variables at once: ($alpha, $beta, $production) = qw(January March August); # move beta to alpha, # move production to beta, # move alpha to production ($alpha, $beta, $production) = ($beta, $production, $alpha); When this code finishes, See AlsoThe section on "List value constructors" in perldata (1) and Chapter 2 of Programming Perl |