【PHP】为项目引入函数级的性能监控
作者:zhanhailiang 日期:2013-03-18
使用PHP扩展Xhprof来实现函数级的性能监控。
引用官方对Xhprof的描述:
XHProf is a function-level hierarchical profiler for PHP and has a simple HTML based navigational interface. The raw data collection component is implemented in C (as a PHP extension). The reporting/UI layer is all in PHP. It is capable of reporting function-level inclusive and exclusive wall times, memory usage, CPU times and number of calls for each function. Additionally, it supports ability to compare two runs (hierarchical DIFF reports), or aggregate results from multiple runs.提供函数级别的性能信息,例如调用次数,其中包括阻塞时间,内存使用情况和CPU时间。1. 安装与配置
<span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software <span class="co0" style="color:rgb(128,128,128); font-style:italic"># wget http://pecl.php.net/get/xhprof-0.9.2.tgz</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software <span class="co0" style="color:rgb(128,128,128); font-style:italic"># tar zxvf xhprof-0.9.2.tgz</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software <span class="co0" style="color:rgb(128,128,128); font-style:italic"># cd xhprof-0.9.2/</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2 <span class="co0" style="color:rgb(128,128,128); font-style:italic"># ls -alp</span>总计 <span class="nu0" style="color:rgb(204,102,204)">968</span>drwxr-xr-x <span class="nu0" style="color:rgb(204,102,204)">6</span> root root <span class="nu0" style="color:rgb(204,102,204)">4096</span> <span class="nu0" style="color:rgb(204,102,204)">2013</span>-03-<span class="nu0" style="color:rgb(204,102,204)">18</span> 09:09 .<span class="sy0" style="color:rgb(102,204,102)">/</span>drwxr-xr-x <span class="nu0" style="color:rgb(204,102,204)">47</span> root root <span class="nu0" style="color:rgb(204,102,204)">8192</span> <span class="nu0" style="color:rgb(204,102,204)">2013</span>-03-<span class="nu0" style="color:rgb(204,102,204)">18</span> 09:09 ..<span class="sy0" style="color:rgb(102,204,102)">/</span><span class="re5">-rw-r--r--</span> <span class="nu0" style="color:rgb(204,102,204)">1</span> <span class="nu0" style="color:rgb(204,102,204)">1425</span> <span class="kw2" style="color:rgb(0,0,0); font-weight:bold">users</span> <span class="nu0" style="color:rgb(204,102,204)">3359</span> <span class="nu0" style="color:rgb(204,102,204)">2009</span>-06-02 01:<span class="nu0" style="color:rgb(204,102,204)">52</span> CHANGELOG<span class="re5">-rw-r--r--</span> <span class="nu0" style="color:rgb(204,102,204)">1</span> <span class="nu0" style="color:rgb(204,102,204)">1425</span> <span class="kw2" style="color:rgb(0,0,0); font-weight:bold">users</span> <span class="nu0" style="color:rgb(204,102,204)">266</span> <span class="nu0" style="color:rgb(204,102,204)">2009</span>-06-02 01:<span class="nu0" style="color:rgb(204,102,204)">52</span> CREDITSdrwxr-xr-x <span class="nu0" style="color:rgb(204,102,204)">2</span> root root <span class="nu0" style="color:rgb(204,102,204)">4096</span> <span class="nu0" style="color:rgb(204,102,204)">2013</span>-03-<span class="nu0" style="color:rgb(204,102,204)">18</span> 09:09 examples<span class="sy0" style="color:rgb(102,204,102)">/</span> <span class="co0" style="color:rgb(128,128,128); font-style:italic"># demo</span>drwxr-xr-x <span class="nu0" style="color:rgb(204,102,204)">8</span> root root <span class="nu0" style="color:rgb(204,102,204)">4096</span> <span class="nu0" style="color:rgb(204,102,204)">2013</span>-03-<span class="nu0" style="color:rgb(204,102,204)">18</span> 09:09 extension<span class="sy0" style="color:rgb(102,204,102)">/</span> <span class="co0" style="color:rgb(128,128,128); font-style:italic"># pecl </span><span class="re5">-rw-r--r--</span> <span class="nu0" style="color:rgb(204,102,204)">1</span> <span class="nu0" style="color:rgb(204,102,204)">1425</span> <span class="kw2" style="color:rgb(0,0,0); font-weight:bold">users</span> <span class="nu0" style="color:rgb(204,102,204)">10174</span> <span class="nu0" style="color:rgb(204,102,204)">2009</span>-06-02 01:<span class="nu0" style="color:rgb(204,102,204)">52</span> LICENSE<span class="re5">-rw-r--r--</span> <span class="nu0" style="color:rgb(204,102,204)">1</span> <span class="nu0" style="color:rgb(204,102,204)">1425</span> <span class="kw2" style="color:rgb(0,0,0); font-weight:bold">users</span> <span class="nu0" style="color:rgb(204,102,204)">186</span> <span class="nu0" style="color:rgb(204,102,204)">2009</span>-06-02 01:<span class="nu0" style="color:rgb(204,102,204)">52</span> README<span class="re5">-rw-r--r--</span> <span class="nu0" style="color:rgb(204,102,204)">1</span> root root <span class="nu0" style="color:rgb(204,102,204)">931660</span> <span class="nu0" style="color:rgb(204,102,204)">2009</span>-06-02 01:<span class="nu0" style="color:rgb(204,102,204)">55</span> xhprofdrwxr-xr-x <span class="nu0" style="color:rgb(204,102,204)">6</span> root root <span class="nu0" style="color:rgb(204,102,204)">4096</span> <span class="nu0" style="color:rgb(204,102,204)">2013</span>-03-<span class="nu0" style="color:rgb(204,102,204)">18</span> 09:09 xhprof_html<span class="sy0" style="color:rgb(102,204,102)">/</span> <span class="co0" style="color:rgb(128,128,128); font-style:italic"># 自带的界面包</span>drwxr-xr-x <span class="nu0" style="color:rgb(204,102,204)">4</span> root root <span class="nu0" style="color:rgb(204,102,204)">4096</span> <span class="nu0" style="color:rgb(204,102,204)">2013</span>-03-<span class="nu0" style="color:rgb(204,102,204)">12</span> <span class="nu0" style="color:rgb(204,102,204)">15</span>:<span class="nu0" style="color:rgb(204,102,204)">40</span> xhprof_lib<span class="sy0" style="color:rgb(102,204,102)">/</span> <span class="co0" style="color:rgb(128,128,128); font-style:italic"># 函数库</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2 <span class="co0" style="color:rgb(128,128,128); font-style:italic"># cd extension/</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2<span class="sy0" style="color:rgb(102,204,102)">/</span>extension <span class="co0" style="color:rgb(128,128,128); font-style:italic"># phpize </span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2<span class="sy0" style="color:rgb(102,204,102)">/</span>extension <span class="co0" style="color:rgb(128,128,128); font-style:italic"># ./configure --with-php-config=/usr/local/services/php/bin/php-config --enable-xhprof</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2<span class="sy0" style="color:rgb(102,204,102)">/</span>extension <span class="co0" style="color:rgb(128,128,128); font-style:italic"># make</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2<span class="sy0" style="color:rgb(102,204,102)">/</span>extension <span class="co0" style="color:rgb(128,128,128); font-style:italic"># make install</span>Installing shared extensions: <span class="sy0" style="color:rgb(102,204,102)">/</span>usr<span class="sy0" style="color:rgb(102,204,102)">/</span>local<span class="sy0" style="color:rgb(102,204,102)">/</span>services<span class="sy0" style="color:rgb(102,204,102)">/</span>php<span class="sy0" style="color:rgb(102,204,102)">/</span>lib<span class="sy0" style="color:rgb(102,204,102)">/</span>php<span class="sy0" style="color:rgb(102,204,102)">/</span>extensions<span class="sy0" style="color:rgb(102,204,102)">/</span>no-debug-non-zts-<span class="nu0" style="color:rgb(204,102,204)">20090626</span><span class="sy0" style="color:rgb(102,204,102)">/</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2<span class="sy0" style="color:rgb(102,204,102)">/</span>extension <span class="co0" style="color:rgb(128,128,128); font-style:italic"># cp /usr/local/services/php/lib/php/extensions/no-debug-non-zts-20090626/xhprof.so /usr/local/services/php/extensions/</span><span class="co0" style="color:rgb(128,128,128); font-style:italic"># 将生成的xhprof.so复制到extension_dir目录下,配置php.ini,重启php-fpm或服务器即可</span> <span class="sy0" style="color:rgb(102,204,102)">//</span> php.ini<span class="br0" style="color:rgb(102,204,102)">[</span>xhprof<span class="br0" style="color:rgb(102,204,102)">]</span><span class="re2" style="color:rgb(0,0,255)">extension</span>=xhprof.soxhprof.output_dir=<span class="st0" style="color:rgb(255,0,0)">"/data/logs/servers/xhprof"</span> <span class="co0" style="color:rgb(128,128,128); font-style:italic"># 检查xhprof是否加载</span><span class="sy0" style="color:rgb(102,204,102)">/</span>data<span class="sy0" style="color:rgb(102,204,102)">/</span>software<span class="sy0" style="color:rgb(102,204,102)">/</span>xhprof-0.9.2<span class="sy0" style="color:rgb(102,204,102)">/</span>extension <span class="co0" style="color:rgb(128,128,128); font-style:italic"># php -m|grep xhprof</span>xhprof2.性能分析与日志记录
首先添加如下代码,以便记录十分之一的请求的性能分析日志(日志记录在/data/logs/servers/xhprof):
<span class="re0" style="color:rgb(0,0,255)">$xhprofEnabled</span> <span class="sy0" style="color:rgb(102,204,102)">=</span> <span class="kw4" style="color:rgb(153,51,51)">FALSE</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span class="kw1" style="color:rgb(177,177,0)">if</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="kw3" style="color:rgb(0,0,102)">extension_loaded</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="st_h">'xhprof'</span><span class="br0" style="color:rgb(102,204,102)">)</span> <span class="sy0" style="color:rgb(102,204,102)">&&</span> <span class="kw3" style="color:rgb(0,0,102)">mt_rand</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="nu0" style="color:rgb(204,102,204)">1</span><span class="sy0" style="color:rgb(102,204,102)">,</span> <span class="nu0" style="color:rgb(204,102,204)">10</span><span class="br0" style="color:rgb(102,204,102)">)</span> <span class="sy0" style="color:rgb(102,204,102)">===</span> <span class="nu0" style="color:rgb(204,102,204)">1</span><span class="br0" style="color:rgb(102,204,102)">)</span> <span class="br0" style="color:rgb(102,204,102)">{</span> <span class="co1" style="color:rgb(128,128,128); font-style:italic">// 分析十分之一的请求性能</span> <span class="co1" style="color:rgb(128,128,128); font-style:italic">// 开启性能监测</span> xhprof_enable<span class="br0" style="color:rgb(102,204,102)">(</span><span class="coMULTI" style="color:rgb(128,128,128); font-style:italic">/*XHPROF_FLAGS_CPU + */</span>XHPROF_FLAGS_MEMORY <span class="sy0" style="color:rgb(102,204,102)">+</span> XHPROF_FLAGS_NO_BUILTINS <span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span> <span class="re0" style="color:rgb(0,0,255)">$xhprofEnabled</span> <span class="sy0" style="color:rgb(102,204,102)">=</span> <span class="kw4" style="color:rgb(153,51,51)">TRUE</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span class="br0" style="color:rgb(102,204,102)">}</span>接着注册请求结束处理器,以便请求结束时记录下xhprof性能分析日志:
<span class="kw2" style="color:rgb(0,0,0); font-weight:bold">function</span><span style="color:#333333"> profile_record</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="br0" style="color:rgb(102,204,102)">)</span><span style="color:#333333"> </span><span class="br0" style="color:rgb(102,204,102)">{</span><span style="color:#333333"> </span><span class="kw1" style="color:rgb(177,177,0)">if</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="kw3" style="color:rgb(0,0,102)">isset</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="re0" style="color:rgb(0,0,255)">$GLOBALS</span><span class="br0" style="color:rgb(102,204,102)">[</span><span class="st_h" style="color:rgb(51,51,51)">'xhprofEnabled'</span><span class="br0" style="color:rgb(102,204,102)">]</span><span class="br0" style="color:rgb(102,204,102)">)</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">&&</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$GLOBALS</span><span class="br0" style="color:rgb(102,204,102)">[</span><span class="st_h" style="color:rgb(51,51,51)">'xhprofEnabled'</span><span class="br0" style="color:rgb(102,204,102)">]</span><span class="br0" style="color:rgb(102,204,102)">)</span><span style="color:#333333"> </span><span class="br0" style="color:rgb(102,204,102)">{</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$xhprof_data</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> xhprof_disable</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$path</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$_SERVER</span><span class="br0" style="color:rgb(102,204,102)">[</span><span class="st_h" style="color:rgb(51,51,51)">'PHP_SELF'</span><span class="br0" style="color:rgb(102,204,102)">]</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span style="color:#333333"> </span><span class="kw1" style="color:rgb(177,177,0)">if</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="re0" style="color:rgb(0,0,255)">$pos</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> </span><span class="kw3" style="color:rgb(0,0,102)">strpos</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="re0" style="color:rgb(0,0,255)">$path</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="st_h" style="color:rgb(51,51,51)">'/htdocs'</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="br0" style="color:rgb(102,204,102)">)</span><span style="color:#333333"> </span><span class="br0" style="color:rgb(102,204,102)">{</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$path</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> </span><span class="kw3" style="color:rgb(0,0,102)">substr</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="re0" style="color:rgb(0,0,255)">$path</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$pos</span><span class="sy0" style="color:rgb(102,204,102)">+</span><span class="nu0" style="color:rgb(204,102,204)">7</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span style="color:#333333"> </span><span class="br0" style="color:rgb(102,204,102)">}</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$basename</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> </span><span class="kw3" style="color:rgb(0,0,102)">str_replace</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="kw3" style="color:rgb(0,0,102)">array</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="st_h" style="color:rgb(51,51,51)">'.'</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="st_h" style="color:rgb(51,51,51)">'/'</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="st_h" style="color:rgb(51,51,51)">'_'</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="kw3" style="color:rgb(0,0,102)">ltrim</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="re0" style="color:rgb(0,0,255)">$path</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="st_h" style="color:rgb(51,51,51)">'/'</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span style="color:#333333"> </span><span class="coMULTI" style="color:rgb(128,128,128); font-style:italic">/* 官方Demo,请参考下载包里的</span><span class="coMULTI" style="font-style:italic"><span style="color:#ff0000">xhprof-0.9.2/examples/sample.php</span></span><span class="coMULTI" style="color:rgb(128,128,128); font-style:italic"> * // * // Saving the XHProf run * // using the default implementation of iXHProfRuns. * // * include_once $XHPROF_ROOT . "/xhprof_lib/utils/xhprof_lib.php"; * include_once $XHPROF_ROOT . "/xhprof_lib/utils/xhprof_runs.php"; * $xhprof_runs = new XHProfRuns_Default(); */</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$xhprof_runs</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> </span><span class="kw2" style="color:rgb(0,0,0); font-weight:bold">new</span><span style="color:#333333"> HWSL_XhProfRuns</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span style="color:#333333"> </span><span class="co1" style="color:rgb(128,128,128); font-style:italic">// 记录日志时引入时间截,方便比较不同版本间的性能差异</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$run_id</span><span style="color:#333333"> </span><span class="sy0" style="color:rgb(102,204,102)">=</span><span style="color:#333333"> </span><span class="re0" style="color:rgb(0,0,255)">$xhprof_runs</span><span class="sy0" style="color:rgb(102,204,102)">-></span><span class="me1" style="color:rgb(0,102,0)">save_run</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="re0" style="color:rgb(0,0,255)">$xhprof_data</span><span class="sy0" style="color:rgb(102,204,102)">,</span><span style="color:#333333"> </span><span class="st_h" style="color:rgb(51,51,51)">'xhprof_itravel_'</span><span class="sy0" style="color:rgb(102,204,102)">.</span><span class="re0" style="color:rgb(0,0,255)">$basename</span><span class="sy0" style="color:rgb(102,204,102)">.</span><span class="st_h" style="color:rgb(51,51,51)">'_'</span><span class="sy0" style="color:rgb(102,204,102)">.</span><span class="kw3" style="color:rgb(0,0,102)">date</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="st_h" style="color:rgb(51,51,51)">'YmdHis'</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span><span style="color:#333333"> </span><span class="br0" style="color:rgb(102,204,102)">}</span><span style="color:#333333"></span><span class="br0" style="color:rgb(102,204,102)">}</span><span style="color:#333333"> </span><span class="kw3" style="color:rgb(0,0,102)">register_shutdown_function</span><span class="br0" style="color:rgb(102,204,102)">(</span><span class="st_h" style="color:rgb(51,51,51)">'profile_record'</span><span class="br0" style="color:rgb(102,204,102)">)</span><span class="sy0" style="color:rgb(102,204,102)">;</span>生成的日志以文件保存在:xhprof.output_dir=”/data/logs/servers/xhprof”
生成的日志文件命名规则为:
. 其中命名空间
的命名规则定义为:'xhprof_itravel_'.$basename.'_'.date('YmdHis') $basename记录相应的文件位置,date(‘YmdHis’)记录当前时间戳,以便比较同一文件不同版本间的性能差异。
3.日志分析
然后,通过官方提供的用户界面包xhprof-0.9.2/xhprof_html/来查看运行报告:
要查看run_id是
和命名空间是 的报告,访问URL: http://
/ index.php?run=&source= 其中各列含义如下:
Inclusive Time (或子树执行时间) :包括子树执行时间的所有执行时间。 Exclusive Time/Self Time :函数执行本身的时间花费。不包括子树执行时间。 Wall时间 :又名经过的时间或挂钟时间。 CPU时间 : CPU时间在用户空间+ CPU时间在内核空间。也可以查看图形化的性能分析报告(其中高亮显示的路径直观反映了函数调用栈中最大的性能损耗路径):
http://
/ callgraph.php?run=&source= 4.扩展阅读
在生产环境中使用php性能测试工具xhprof 关于改善xhprof使用情况的设想 XHProf文件(草稿)

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。

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。

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。

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。

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。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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