#!/usr/bin/perl
$a = "1234";
@b = reverse($a);
$c = reverse($a);
print @b,"\n";                  #1234
print $c,"\n";                  #4321
print reverse($a),"\n";         #1234   
print scalar reverse($a),"\n";  #4321
print reverse($a)."\n";         #4321

首先我们要明确两个函数print和reverse的在perl中的定义（以下是perldoc中的解释）

print FILEHANDLE LIST

print LIST

Because print takes a LIST,anything in the LIST is evaluated in list context.

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reverse LIST

In list context,returns a list value consisting of the elementsof LIST in the opposite order. In scalar context,concatenates theelements of LIST and returns a string value with all charactersin the opposite order.

从以上可以看出，print reverse(1234);其实是print LIST，那么reverse的参数也会被当作一个list，即只有一个元素的列表(1234)，那么反转后还是1234。

如果想将结果反转成4321，就必须转成标量上下文，如上面程序中scalar ，或者用.连接一个字符串。