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  • perl last next redo区别

    last: 立即中止循环,就像C语言中的break
    
    next:
    
    有时候并不要求立刻退出循环,但是需要立刻结束当前这次迭代,这就是next操作符的用处,
    
    
    它会跳到内层循环块的底端。在next之后,程序将会继续执行循环的下次迭代
    
    
    
    
    redo操作符:
    
    redo,它能将控制返回到本次循环的顶端,不经过任何条件测试,也不会进入下一次循环迭代。
    
    redo 则会重新执行这次的迭代,
    
    next:而next会继续下一次迭代
    
    [oracle@jhoa 7]$ cat 7.pl  
    for ($i = 1;$i <= 10;$i++){ #从1数到10
    next if ($i == 5);
      print "I can count to $i!
    ";
    }
    
    [oracle@jhoa 7]$ perl 7.pl 
    I can count to 1!
    I can count to 2!
    I can count to 3!
    I can count to 4!
    I can count to 6!
    I can count to 7!
    I can count to 8!
    I can count to 9!
    I can count to 10!
    
    last:
    
    
    [oracle@jhoa 7]$ cat 10.pl 
    for ($i = 1;$i <= 10;$i++){ #从1数到10
    if ($i == 5){last;}
    else{
      print "I can count to $i!
    ";
    }}
    
    [oracle@jhoa 7]$ perl 10.pl 
    I can count to 1!
    I can count to 2!
    I can count to 3!
    I can count to 4!
    
    redo:
    
    [oracle@jhoa 7]$ cat 10.pl 
    for ($i = 1;$i <= 10;$i++){ #从1数到10
     if ($i == 5){redo;}
    else{
      print "I can count to $i!
    ";
    }}
    [oracle@jhoa 7]$ perl -w 10.pl 
    I can count to 1!
    I can count to 2!
    I can count to 3!
    I can count to 4!
    

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  • 原文地址:https://www.cnblogs.com/hzcya1995/p/13352068.html
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