<script>
function check() {
var reg = /^(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))\.(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))\.(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))\.(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))$/;
if (reg.test(t1.value)){
alert('right!');
}
else {
alert('error!');
}
}
</script><input type="text" value="127.0.0.1" id="t1">
<input type="button" value="check" onclick="check();">
function check() {
var reg = /^(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))\.(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))\.(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))\.(\d{1}|\d{2}|([0-1][0-9][0-9]|[0-2][0-5][0-5]))$/;
if (reg.test(t1.value)){
alert('right!');
}
else {
alert('error!');
}
}
</script><input type="text" value="127.0.0.1" id="t1">
<input type="button" value="check" onclick="check();">
$e="(1[0-9]{2}|[1-9]?[0-9]|2[0-4][0-9]|25[0-5])";
if(ereg("^$e\.$e\.$e\.$e$",$ip)){
echo $ip."通过<br/>";
}
else
echo $ip."错误<br/>";
}
checkIP("100.210.0.45");
checkIP("101.210.00.45");
checkIP("101.256.0.45");
checkIP("101.255.0.415");
http://expert.csdn.net/Expert/topic/1094/1094708.xml?temp=.5813257