?????? ?????

????????ж?
?????????
 1??while???
 2??until???
 3??for???
 4??????б?(????)???????foreach???
 5??do???
 6?????????
 7???????goto???
????????????

????????ж?
 if ( <expression>) {
 <statement_block_1>
 }
 elsif ( <expression> ) {
 <statement_block_2>
 }
 ...
 else{
 <statement_block_3>
 }
?????????
1??while???
 while ( <expression> ) {
 <statement_block>
 }
2??until???
 until ( <expression> ) {
 <statement_block>
 }
3????C??for??? ????
 for ($count=1; $count <= 5; $count++) {
 # statements inside the loop go here
 }
????????for???????????????????????
 for ($line = <STDIN>, $count = 1; $count <= 3; $line = <STDIN>, $count++) {
 print ($line);
 }
??????????????
 $line = <STDIN>;
 $count = 1;
 while ($count <= 3) {
 print ($line);
 $line = <STDIN>;
 $count++;
 }
4??????б?(????)????????????foreach?? ?????
 foreach localvar (listexpr) {
 statement_block;
 }
????
 foreach $word (@words) {
 if ($word eq "the") {
 print ("found the word 'the'\n");
 }
 }
???
(1)????????????localvar?????????????????????????????????????????????
(2)??????и????????????????????????????磺
 @list = (1, 2, 3, 4, 5);
 foreach $temp (@list) {
 if ($temp == 2) {
 $temp = 20;
 }
 }
???@list??????(1, 20, 3, 4, 5)??
5??do???
 do {
 statement_block
 } while_or_until (condexpr);
 do??????????????????
6?????????
 ???????last????C?е?break?????????????????????next????C?е?continue?????????PERL???е??????????redo???京?????????????????????????????????????????????redo??????do????в??????á?
7???????goto label;???

????????????
 ???statement keyword condexpr??????keyword???if??unless??while??until???磺
 print ("This is zero.\n") if ($var == 0);
 print ("This is zero.\n") unless ($var != 0);
 print ("Not zero yet.\n") while ($var-- > 0);
 print ("Not zero yet.\n") until ($var-- == 0);
 ????????ж?д????棬?????????е??

????? ????? ??

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