#!/usr/bin/perl 

$name="aAbBcCbB";
$_="aAbBcCbB";

print "------first--------\n";
if(/bB/){        # 匹配完第一个bB就结束
    print "pre match: $` \n";
    print "match: $& \n";
    print "post match: $' \n";
}

print "------while--------\n";
while(/bB/g){   # 将迭代两次
    print "pre match: $` \n";
    print "match: $& \n";
    print "post match: $' \n";
}