Looping
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Basics
Most looping constructs in Perl are quite similar to those of
C/C++. The one major difference is that Perl always requires opening and
closing braces ({}), even if the loop contains only one
executable Perl statement.
foreach Loops
The foreach construct is similar to the C shell's
foreach thingy. The general syntax is:
<![CDATA[
foreach [$loop_var] (@list)
{
# expression(s)
}
]]>
This loop will itterate over the entire length of the list, from
beginning to end, setting $loop_var to consecutive
elements of @list. If $loop_var is omitted,
$_ is set. @list ca be any list, including
functions that return a list.
for Loops
for loops are identical to their C/C++ counterparts, so
the syntax is the very familiar:
<![CDATA[
for (init_expression; loop_condition; loop_expression)
{
# expression(s)
}
]]>
and as a simple example:
<![CDATA[
for ($i = 0; $i < $length; $i++)
{
print "inc = $inc[$i]\n";
}
]]>
while, do/until and
do/while Loops
A while loop has the following syntax:
<![CDATA[
while (expression)
{
# expression(s)
}
]]>
and will continue until expression becomes
true. The do/while loop construct is, again, similar to the C/C++
loops, and has the form:
<![CDATA[
do
{
# expression(s)
}
while (expression)
]]>
You could substitute until (expression) in the
do/while loop above for a different flavor of looping
(ie, the compliment of the do/while).
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Last Modified: $Date: 1997/05/02 07:17:43 $