Perl 迴圈嵌套
Perl 迴圈Perl 語言允許在一個迴圈內使用另一個迴圈，下麵演示幾個實例來說明這個概念。
語法
嵌套 for 迴圈語句的語法：
for ( init; condition; increment ){
for ( init; condition; increment ){
statement(s);
}
statement(s);
}
嵌套 while 迴圈語句的語法：
while(condition){
while(condition){
statement(s);
}
statement(s);
}
嵌套 do...while 迴圈語句的語法：
do{
statement(s);
do{
statement(s);
}while( condition );
}while( condition );
嵌套 until 迴圈語句的語法：
until(condition){
until(condition){
statement(s);
}
statement(s);
}
嵌套 foreach 迴圈語句的語法：
foreach $a (@listA){
foreach $b (@listB){
statement(s);
}
statement(s);
}
實例
#!/usr/bin/perl
$a = 0;
$b = 0;
# 外部迴圈
while($a < 3){
$b = 0;
# 內部迴圈
while( $b < 3 ){
print "a = $a, b = $b\n";
$b = $b + 1;
}
$a = $a + 1;
print "a = $a\n\n";
}
執行以上程式，輸出結果為：
a = 0, b = 0 a = 0, b = 1 a = 0, b = 2 a = 1 a = 1, b = 0 a = 1, b = 1 a = 1, b = 2 a = 2 a = 2, b = 0 a = 2, b = 1 a = 2, b = 2 a = 3