随笔档案

pr("abc".matches(""));
        pr("a8729a".replaceAll("\\d", "-"));
        Pattern p = Pattern.compile("\\w{3}");
        Matcher m = p.matcher("dth");
        pr(m.matches());
        
        pr("aaaaaaaa".matches("a*"));
        pr("aaaa".matches("a+"));
        pr("".matches("a*"));
        pr("a".matches("a?"));
        pr("".matches("a?"));
        pr("3235364546757555".matches("\\d{3,100}"));
        pr("192245".matches("\\d{1,3}[0-2][0-9][0-9]"));
        pr("a".matches("[^fjkl]"));
        pr("R".matches("[A-Z&&[RFG]]"));
        pr("shivareemmsdo_1018".matches("\\w{6,20}"));
        pr("\\".matches("\\\\{0,5}"));
        
        pr("hello sir!".matches("^h.*"));
        pr("hello sir!".matches(".*r!$"));
        pr("hello sir!".matches("^h[a-z]{1,}\\b.*r!$"));
        pr("hello sir!".matches("^h.*r!$"));

* 零次或多次
+ 一此或多次
？零次或一次

在JAVA中“\”需要“\\”来表示
在正则表达式中一个“\”需要“\\\\”来表示

“^”位于[]里意思是取反，位于[]外面意思是输入都开始。$代表结尾。

用正则表达式验证ip地址和身份证代码实例如下：
<script language="javascript">
function checkIP()
{
obj=document.getElementById("ip").value
//ip地址
//var exp=/^(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1

\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])$/;
//身份证
//var exp=/\b(((?!\d\d\d)\d+|1\d\d|2[0-4]\d|25[0-5])(\b|\.)){4}/
//var exp=/^(\d{15}|\d{17}[x0-9])/
var exp=/^([\d]{15}|[\d]{18}|[\d]{17}[x|X])$/
var reg = obj.match(exp);
if(reg==null)
{
alert("IP地址不合法！");
}
else
{
alert("IP地址合法！");
}
}
</script>
请输入IP地址：<input type="text" id="ip">
<input type="button" onclick="checkIP()" value="验证">