正则表达式
匹配中文字符的正则表达式: [\u4e00-\u9fa5]匹配双字节字符(包括汉字在内): [^\x00-\xff]
应用:计算字符串的长度(一个双字节字符长度计2,ASCII字符计1)
匹配空行的正则表达式: \n[\s| ]*\r
匹配HTML标记的正则表达式: /.*|/
匹配首尾空格的正则表达式: (^\s*)|(\s*$)
应用:javascript中没有像vbscript那样的trim函数,我们就可以利用这个表达式来实现,如下:
return this.replace(/(^\s*)|(\s*$)/g, "");
}
利用正则表达式分解和转换IP地址:
下面是利用正则表达式匹配IP地址,并将IP地址转换成对应数值的javascript程序:
re=/(\d )\.(\d )\.(\d )\.(\d )/g //匹配IP地址的正则表达式
if(re.test(ip)) {
return RegExp.*Math.pow(255,3)) RegExp.*Math.pow(255,2)) RegExp.*255 RegExp.*1
}
else {
throw new Error("Not a valid IP address!")
}
}
不过上面的程序如果不用正则表达式,而直接用split函数来分解可能更简单,程序如下:
ip=ip.split(".")
alert("IP值是:" (ip[0]*255*255*255 ip[1]*255*255 ip[2]*255 ip[3]*1))
匹配Email地址的正则表达式: \w ([- .]\w )*@\w ([-.]\w )*\.\w ([-.]\w )*
匹配网址URL的正则表达式: http://([\w-] \.) [\w-] (/[\w- ./?%&=]*)?
利用正则表达式去除字串中重复的字符的算法程序:
var s1=s.replace(/(.).*/g,"")
var re=new RegExp("[" s1 "]","g")
var s2=s.replace(re,"")
alert(s1 s2) //结果为:abcefgi
用正则表达式从URL地址中提取文件名的javascript程序,如下结果为page1
s=s.replace(/(.*\/)([^\.] ).*/ig,"")
alert(s)
利用正则表达式限制网页表单里的文本框输入内容:
用正则表达式限制只能输入中文:
用正则表达式限制只能输入全角字符:
用正则表达式限制只能输入数字:
用正则表达式限制只能输入数字和英文:

PHPsessionstrackuserdataacrossmultiplepagerequestsusingauniqueIDstoredinacookie.Here'showtomanagethemeffectively:1)Startasessionwithsession_start()andstoredatain$_SESSION.2)RegeneratethesessionIDafterloginwithsession_regenerate_id(true)topreventsessi

In PHP, iterating through session data can be achieved through the following steps: 1. Start the session using session_start(). 2. Iterate through foreach loop through all key-value pairs in the $_SESSION array. 3. When processing complex data structures, use is_array() or is_object() functions and use print_r() to output detailed information. 4. When optimizing traversal, paging can be used to avoid processing large amounts of data at one time. This will help you manage and use PHP session data more efficiently in your actual project.

The session realizes user authentication through the server-side state management mechanism. 1) Session creation and generation of unique IDs, 2) IDs are passed through cookies, 3) Server stores and accesses session data through IDs, 4) User authentication and status management are realized, improving application security and user experience.

Tostoreauser'snameinaPHPsession,startthesessionwithsession_start(),thenassignthenameto$_SESSION['username'].1)Usesession_start()toinitializethesession.2)Assigntheuser'snameto$_SESSION['username'].Thisallowsyoutoaccessthenameacrossmultiplepages,enhanc

Reasons for PHPSession failure include configuration errors, cookie issues, and session expiration. 1. Configuration error: Check and set the correct session.save_path. 2.Cookie problem: Make sure the cookie is set correctly. 3.Session expires: Adjust session.gc_maxlifetime value to extend session time.

Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.


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