perl - For 循环如何在 perl 中工作

Question

#!/usr/bin/perl
@lines = `perldoc -u -f atan2`;
foreach (@lines) {
  s/\w<([^>]+)>/\U$1/g;
  print;
}

表达式s/\w<([^>]+)>/\U$1/g;工作吗？

Answer 1

替换是这样做的:

s/             
    \w<         # look for a single alphanumeric character followed by <
    ([^>]+)     # capture one or more characters that are not <
    >           # followed by a >
/               ### replace with
   \U           # change following text to uppercase
   $1           # the captured string from above
/gx             # /g means do this as many times as possible per line

我添加了 /x 修饰符以便能够可视化正则表达式。字符类 [^>] 被取反，由 [ 后面的 ^ 字符表示，表示“除了 之外的任何字符>”。

例如，在 perldoc 命令的输出中

X<atan2> X<arctangent> X<tan> X<tangent>

改为

ATAN2 ARCTANGENT TAN TANGENT