在用PHP5.3以上的PHP版本时，只要是涉及时间的会报一个
我在使用
<?
echo date('Y-m-d');
?>
提示
"PHP Warning: date() [function.date]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'UTC' for '8.0/no DST' instead in"
实际上，从 PHP 5.1.0 ，当对使用date()等函数时，如果timezone设置不正确，在每一次调用时间函数时,都会产生E_NOTICE 或者 E_WARNING 信息。而又在php5.1.0中，date.timezone这个选项，默认情况下是关闭的，无论用什么php命令都是格林威治标准时间，但是PHP5.3中好像如果没有设置也会强行抛出了这个错误的,解决此问题，只要本地化一下，就行了。
以下是三种方法(任选一种都行)：
一、在页头使用date_default_timezone_set()设置 date_default_timezone_set('PRC'); //东八时区 echo date('Y-m-d H:i:s');
二、在页头使用 ini_set('date.timezone','Asia/Shanghai');
三、修改php.ini。打开php5.ini查找date.timezone 去掉前面的分号修改成为：date.timezone =PRC
本文章来给各位同学介绍Fatal error: session_start(): Failed to initialize storage module: files问题的解决办法。原创解决： Fatal error: session_start(): Failed to initialize storage module: files问题
之前编译安装的LNMP环境+phpmyamdin4.02的版本，今天突然出现这个问题：
Fatal error: session_start(): Failed to initialize storage module: files (path: ) in /data/www/phpmyadmin/libraries/session.inc.php on line 83
大致意思是session会话初始化的时候储存路径有误！第一反应就是查看php.ini的配置文件中的：
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默认前面是加的分号，表示不启用，我之前配置的时候已经启用了。那为什么还会报错呢？，于是网上找了一些资料，感觉都千篇一律：
1、检查error.log(Apache2.2logs)文件，查看是否有错误报告。未发现。
2、检查php.ini中的session.save_handler的值是否为files，如果不是改为files
3、检查php.ini文件中session.save_path是否被注释了，如果有，则去掉前面的”;”。
4、将save_path后面的路径改成已有的路径，比如”D:phptemp”
5、检查temp文件夹的属性是否可读可写。
6、重启APACHE服务器。OK
不知道那些哥们转载的时候自己试过了没有（在这里喷一下，最讨厌那种自己都没有亲测，就一股脑的转来转去。一点都不负责!）
根据上面的流程，排查了之后发现压根就没有解决，不过璞玉的服务器是nginx非apache。
然后自己写了一个脚本test.php：
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| $r = session_start(); var_dump($r); | |
打印结果为：
Warning: session_start(): SAFE MODE Restriction in effect. The script whose uid is 501 is not allowed to access /tmp owned by uid 0 in /data/www/test.php on line 3 Fatal error: session_start(): Failed to initialize storage module: files (path: ) in /data/www/test.php on line 3
意思是 php5一个安全模式的bug，默认session的save_path是系统的临时目录，这样会要校验权限。而这个脚本不能通过/tmp拥有者uid为0来执行uid是501也是www用户组的权限
解决这个有两种解决方法：
1。关闭安全模式；
2。在命令行下chown改文件/目录的拥有者
当然两种方法都要求你有服务器的权限。
下面是璞玉php.ini的配置文件：
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[Session] ; Handler used to store/retrieve data. ; http://php.net/session.save-handler session.save_handler = files; Argument passed to save_handler. In the case of files, this is the path ; where data files are stored. Note: Windows users have to change this ; variable in order to use PHP's session functions. ; ; The path can be defined as: ; ; session.save_path = "N;/path" ; ; where N is an integer. Instead of storing all the session files in ; /path, what this will do is use subdirectories N-levels deep, and ; store the session data in those directories. This is useful if you ; or your OS have problems with lots of files in one directory, and is ; a more efficient layout for servers that handle lots of sessions. ; ; NOTE 1: PHP will not create this directory structure automatically. ; You can use the script in the ext/session dir for that purpose. ; NOTE 2: See the section on garbage collection below if you choose to ; use subdirectories for session storage ; ; The file storage module creates files using mode 600 by default. ; You can change that by using ; ; session.save_path = "N;MODE;/path" ; ; where MODE is the octal representation of the mode. Note that this ; does not overwrite the process's umask. ; http://php.net/session.save-path session.save_path = "/tmp" ; Whether to use cookies. ; http://php.net/session.use-cookies session.use_cookies = 1 ; http://php.net/session.cookie-secure ;session.cookie_secure = ; This option forces PHP to fetch and use a cookie for storing and maintaining ; the session id. We encourage this operation as it's very helpful in combatting ; session hijacking when not specifying and managing your own session id. It is ; not the end all be all of session hijacking defense, but it's a good start. ; http://php.net/session.use-only-cookies session.use_only_cookies = 1 ; Name of the session (used as cookie name). ; http://php.net/session.name session.name = PHPSESSID ; Initialize session on request startup. ; http://php.net/session.auto-start session.auto_start = 0 ; Lifetime in seconds of cookie or, if 0, until browser is restarted. ; http://php.net/session.cookie-lifetime session.cookie_lifetime = 0 ; The path for which the cookie is valid. ; http://php.net/session.cookie-path session.cookie_path = / ; The domain for which the cookie is valid. ; http://php.net/session.cookie-domain session.cookie_domain = ; Whether or not to add the httpOnly flag to the cookie, which makes it inaccessible to browser scripting languages such as JavaScript. ; http://php.net/session.cookie-httponly session.cookie_httponly = ; Handler used to serialize data. php is the standard serializer of PHP. ; http://php.net/session.serialize-handler session.serialize_handler = php ; Defines the probability that the 'garbage collection' process is started ; on every session initialization. The probability is calculated by using ; gc_probability/gc_divisor. Where session.gc_probability is the numerator ; and gc_divisor is the denominator in the equation. Setting this value to 1 ; when the session.gc_divisor value is 100 will give you approximately a 1% chance ; the gc will run on any give request. ; Default Value: 1 ; Development Value: 1 ; Production Value: 1 ; http://php.net/session.gc-probability session.gc_probability = 1 ; Defines the probability that the 'garbage collection' process is started on every ; session initialization. The probability is calculated by using the following equation: ; gc_probability/gc_divisor. Where session.gc_probability is the numerator and ; session.gc_divisor is the denominator in the equation. Setting this value to 1 ; when the session.gc_divisor value is 100 will give you approximately a 1% chance ; the gc will run on any give request. Increasing this value to 1000 will give you ; a 0.1% chance the gc will run on any give request. For high volume production servers, ; this is a more efficient approach. ; Default Value: 100 ; Development Value: 1000 ; Production Value: 1000 ; http://php.net/session.gc-divisor session.gc_divisor = 1000 ; After this number of seconds, stored data will be seen as 'garbage' and ; cleaned up by the garbage collection process. ; http://php.net/session.gc-maxlifetime session.gc_maxlifetime = 1440 ; NOTE: If you are using the subdirectory option for storing session files ; (see session.save_path above), then garbage collection does *not* ; happen automatically. You will need to do your own garbage ; collection through a shell script, cron entry, or some other method. ; For example, the following script would is the equivalent of ; setting session.gc_maxlifetime to 1440 (1440 seconds = 24 minutes): ; find /path/to/sessions -cmin +24 | xargs rm ; PHP 4.2 and less have an undocumented feature/bug that allows you to ; to initialize a session variable in the global scope, even when register_globals ; is disabled. PHP 4.3 and later will warn you, if this feature is used. ; You can disable the feature and the warning separately. At this time, ; the warning is only displayed, if bug_compat_42 is enabled. This feature ; introduces some serious security problems if not handled correctly. It's ; recommended that you do not use this feature on production servers. But you ; should enable this on development servers and enable the warning as well. If you ; do not enable the feature on development servers, you won't be warned when it's ; used and debugging errors caused by this can be difficult to track down. ; Default Value: On ; Development Value: On ; Production Value: Off ; http://php.net/session.bug-compat-42 session.bug_compat_42 = Off ; This setting controls whether or not you are warned by PHP when initializing a ; session value into the global space. session.bug_compat_42 must be enabled before ; these warnings can be issued by PHP. See the directive above for more information. ; Default Value: On ; Development Value: On ; Production Value: Off ; http://php.net/session.bug-compat-warn session.bug_compat_warn = Off ; Check HTTP Referer to invalidate externally stored URLs containing ids. ; HTTP_REFERER has to contain this substring for the session to be ; considered as valid. ; http://php.net/session.referer-check session.referer_check = ; How many bytes to read from the file. ; http://php.net/session.entropy-length session.entropy_length = 0 ; Specified here to create the session id. ; http://php.net/session.entropy-file ; On systems that don't have /dev/urandom /dev/arandom can be used ; On windows, setting the entropy_length setting will activate the ; Windows random source (using the CryptoAPI) ;session.entropy_file = /dev/urandom ; Set to {nocache,private,public,} to determine HTTP caching aspects ; or leave this empty to avoid sending anti-caching headers. ; http://php.net/session.cache-limiter session.cache_limiter = nocache ; Document expires after n minutes. ; http://php.net/session.cache-expire session.cache_expire = 180 ; trans sid support is disabled by default. ; Use of trans sid may risk your users security. ; Use this option with caution. ; - User may send URL contains active session ID ; to other person via. email/irc/etc. ; - URL that contains active session ID may be stored ; in publically accessible computer. ; - User may access your site with the same session ID ; always using URL stored in browser's history or bookmarks. ; http://php.net/session.use-trans-sid session.use_trans_sid = 0 ; Select a hash function for use in generating session ids. ; Possible Values ; 0 (MD5 128 bits) ; 1 (SHA-1 160 bits) ; This option may also be set to the name of any hash function supported by ; the hash extension. A list of available hashes is returned by the hash_algos() ; function. ; http://php.net/session.hash-function session.hash_function = 0 ; Define how many bits are stored in each character when converting ; the binary hash data to something readable. ; Possible values: ; 4 (4 bits: 0-9, a-f) ; 5 (5 bits: 0-9, a-v) ; 6 (6 bits: 0-9, a-z, A-Z, "-", ",") ; Default Value: 4 ; Development Value: 5 ; Production Value: 5 ; http://php.net/session.hash-bits-per-character session.hash_bits_per_character = 5 ; The URL rewriter will look for URLs in a defined set of HTML tags. ; form/fieldset are special; if you include them here, the rewriter will ; add a hidden <input> field with the info which is otherwise appended ; to URLs. If you want XHTML conformity, remove the form entry. ; Note that all valid entries require a "=", even if no value follows. ; Default Value: "a=href,area=href,frame=src,form=,fieldset=" ; Development Value: "a=href,area=href,frame=src,input=src,form=fakeentry" ; Production Value: "a=href,area=href,frame=src,input=src,form=fakeentry" ; http://php.net/url-rewriter.tags url_rewriter.tags = "a=href,area=href,frame=src,input=src,form=fakeentry" |
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因为这个是在一台VPS上面配置的，上面有多个项目，于是璞玉打开一个项目，发现此项
目的验证码功能是OK的。
于是查看代码如下：
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上面这个代码是在session_start() 初始化之前来判断是否存在session会话的文件夹。
于是就在phpmyadmin里面的保存的那个文件/phpmyadmin/libraries/session.inc.php做了下修改:
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在 session_start(); 前面添加了 session_save_path(“/data/www/session”); 就解决了这个问题。
切记通过@ini_set(‘session.save_path’, ”/data/www/session”);无效！
这个问题困扰了我几个小时，终于解决了，所以就记录下来，对日后应该会有帮助。
如果对你有帮助，请留言。如果有什么意见欢迎交流！
错误提示
Fatal error: Cannot redeclare class ….
从字面来看也很好理解，说明是重复定义了类，找了一下自己的代码，是因为存在同名的类导致的，修改了类名就好了。
原因分析
1.在同一个文件中重复声明了两次同名的类：
例如：
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| <?php class Foo {} // some code here class Foo {} ?> |
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在第二个 Foo 的地方就会报错。
解决：去掉第二个Foo，或者重命名。
为了防止重复定义，可以在定义一个新的类的时候判断一下这个类是否已经存在：
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| if(class_exists('SomeClass') != true) { //put class SomeClass here } if(class_exists('SomeClass') != true) { //put class SomeClass here } |
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2.重复包含相同的类文件：
例如：对于某个类文件some_class.php，在a.php中
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include "some_class.php"; |
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在b.php中
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就会报错。
解决：将上述的include全部替换为include_once
3.该类为PHP类库中内置的类。
判断方法：在一个空文件中写入
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| <?php class Com { } ?> |
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这时候提示Cannot redeclare class Com，说明这个类就是PHP内置的类。不能使用。
另外，要避免使用太大众化的类名，比如Com，这个类在Linux使用可能是正常的，在Windows环境却无法运行。
再记一个网上找到的解决方法，可能在某些场合有用，先记着
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上面的办法不适用于使用了php __autoload类加载的方法 ,但己经可以解决办法问题了，__autoload是自动加载的我们只要把相同类名找出来然后重命名即可。
今天白天才架起PHPStorm+xdebug的调试环境，就遇到了各式各样的问题：访问超慢响应、访问超快响应但是是空白页。
问题A解决的方法很多，总归还有解决办法；问题B我估计是线程问题，也许可以通过调试php.ini的配置搞定，也许不是，很难讲清楚，线程的问题可能要跟xdebug的版本扯上关系。
解决方式
PHP.ini 找到memory_limit参数，增大！
换一个浏览器！我之前一直用Google Chrome调试程序，之后就开始变慢下来，直到每个页面变成6秒才加载完毕，已经忍无可忍。换成了Firefox、IE均没有这个问题。 （这个方法很好用，还能立刻见效！）
使用 xdebug.profiler_enable_trigger配置，有选择的运行xdebug功能探查程序。
xdebug.remote_host 的值最好跟你服务器的IP一致，比方说你是通过localhost访问，则这里写localhost，你是127.0.0.1访问，就写127.0.0.1
看看你的xdebug.profiler_output_dir目录是否已经达到几G了？（一套电商程序很可能在持续开发十几个小时后，xdebug.profiler_output_dir目录的xdebug文件达到好几G！）
平时不需要的时候，最好关闭xdebug！
xdebug.remote_enable = 0
xdebug.profiler_enable = 0
xdebug.remote_autostart = false
最后，一句话：DON’T RUN XDEBUG ON PRODUCTION.
php中使用内置的reset函数可以获取array的第一个元素的值。例如：
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$arr = array('one', 'two', 'three'); echo reset($arr); |
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// 输出的结果为 one对于下述代码，如果php开启了"Strict Standards"，将会看到"Strict Standards: Only variables should be passed by reference in"的提示。
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$str = 'netingcn.com'; echo reset(explode('.', $str)); |
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为什么会这样呢？可以先看看reset函数的定义：
function reset (array &$array) {}从定义中可以看到，reset接受的参数是一个array的引用。而上述代码中explode返回值不是任何array的引用，所以在"Strict Standards"下会有上述提示。解决办法很简单，只需要把reset(explode('.', $str))分两步写即可。第一步先把explode的返回值赋给一个变量，第二步把这个变量作为reset参数。
出现上面的提示的不只是reset函数，只要参数接受的是对象引用，而传值直接使用function返回值都会看到那样的提示。例如内置的array_pop、shuffle、curent、next、prev、next等等