


php method to find the start and end IP address of a network segment, phpip
This article describes the example of php method to find the start and end IP address of a network segment. Share it with everyone for your reference. The details are as follows:
For example: network segment (192168.1.5/24), its subnet mask is divided according to 24:
11111111.11111111.11111111.00000000(255.255.255.0)
Note: The IP address is 32 bits. 24 in the network segment means that there are 24 1s in the front and 8 0s in the back.
The algorithm of the starting IP address is: the binary number of 192.168.1.5 is ANDed with the binary number of the subnet mask.
The algorithm for ending the IP address is: first invert the binary number of the subnet mask, and then perform an "OR" operation with the binary number of 192.168.1.5
In actual applications, the network address and broadcast address are obtained. The network address 1 is the first host address, and the broadcast address -1 is the last host address.
<?php function mask2bin($n) { $n = intval($n); if($n<0||$n>32) die('error submask'); return str_repeat("1", $n).str_repeat("0",32-$n); } function revBin($s) { $p=array('0','1','2'); $r=array('2','0','1'); return str_replace($p,$r,$s); } function startIp($str,$bSub) { $bIp = decbin($str); $bIp = str_pad($bIp,8,"0",STR_PAD_LEFT); $sIp = bindec($bIp & $bSub); return $sIp; } function endIp($str,$bSub) { $bIp = decbin($str); $bIp = str_pad($bIp,8,"0",STR_PAD_LEFT); $eIp = bindec($bIp | revBin($bSub)); return $eIp; } $ip = array('192','168','1','5');//设定IP地址,可以从表单获取,这里只作演示 $mask = '24'; //设置掩码 $bSub = mask2bin($mask); //将子网掩码转换二进制 $mask = array(); $mask[] = substr($bSub,"0",8); //将子网掩码每8位分一段 $mask[] = substr($bSub,"8",8); $mask[] = substr($bSub,"16",8); $mask[] = substr($bSub,"24",8); echo '<table summary="result" border="1" cellspacing="1" cellpadding="0" > <tbody> <td align="right" ><font size="2">掩码:</font></td> <td> <font size="2">'; for ($i=0;$i<4;$i++) { echo bindec($mask[$i]); if($i!=3) echo "."; } echo '</font> </td> </tr> <tr> <td align="right"><font size="2">网络地址:</font></td> <td> <font size="2">'; for ($i=0;$i<4;$i++) { echo startIp($ip[$i],$mask[$i]); if($i!=3) echo "."; } echo '</font> </td> </tr> </td> </tr> <tr> <td align="right"><font size="2">第一个可用:</font></td> <td> <font size="2">'; for ($i=0;$i<3;$i++) { echo startIp($ip[$i],$mask[$i]); echo "."; } $ip_4 = startIp($ip[3],$mask[3]); echo ++$ip_4; echo '</font> </td> </tr> <tr> <td align="right"><font size="2">最后可用:</font></td> <td> <font size="2">'; for ($i=0;$i<3;$i++) { echo endIp($ip[$i],$mask[$i]); echo "."; } $ip_4 = endIp($ip[3],$mask[3]); echo --$ip_4; echo ' </font> </td> </tr> <tr> <td align="right"><font size="2">广播地址:</font></td> <td> <font size="2">'; for ($i=0;$i<4;$i++) { echo endIp($ip[$i],$mask[$i]); if($i!=3) echo "."; } ?>
I hope this article will be helpful to everyone’s PHP programming design.

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

php判断有没有小数点的方法:1、使用“strpos(数字字符串,'.')”语法,如果返回小数点在字符串中第一次出现的位置,则有小数点;2、使用“strrpos(数字字符串,'.')”语句,如果返回小数点在字符串中最后一次出现的位置,则有。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。


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