perl - "last"在 Perl 中做什么？

Question

在下面的代码中，last 做了什么？在while循环中做什么？我明白，如果 $matrix[$i][$j]{pointer}变量等于 "none"它叫 last但它有什么作用呢？

另外，为什么 $matrix 变量使用花括号包含 score 和 pointer ？ {score} ，我将其视为数组中的第 3 维，但这是其他内容吗？在谷歌上找不到任何关于此的信息。谢谢!

my @matrix;
$matrix[0][0]{score}   = 0;
$matrix[0][0]{pointer} = "none";
#populate $matrix with more stuff

while (1) {
  last if $matrix[$i][$j]{pointer} eq "none"; #<-what is this "last" doing?
  #do some more stuff here
}

Answer 1

last 的可用用途命令:

最后一个标签

最后EXPR

最后

根据 Perl 的 documentation :

The last command is like the break statement in C (as used in loops); it immediately exits the loop in question. If the LABEL is omitted, the command refers to the innermost enclosing loop. The last EXPR form, available starting in Perl 5.18.0, allows a label name to be computed at run time, and is otherwise identical to last LABEL . The continue block, if any, is not executed:

 LINE: while (<STDIN>) {
        last LINE if /^$/;  # exit when done with header
        #...
    }

last cannot be used to exit a block that returns a value such as eval {} , sub {} , or do {} , and should not be used to exit a grep or map operation. Note that a block by itself is semantically identical to a loop that executes once. Thus last can be used to effect an early exit out of such a block.