perl语言正则表达式不区分大小写：/i

xiaoliu

要创建一个大小写无关的模式，如匹配FRED 时，也能匹配上fred, Fred，可以使用修饰符/i：
print “Would you like to play a game?”;
chomp($_ = <STDIN>);
if(/yes/i) {#大小写无关
print “In that case, I recommend that you go bowling.\n”;
}