PHP把下划线分隔命名的字符串转换成驼峰式命名方式（带10万次执行效率测试结果）

<?php//微妙时间function microtime_float(){    list($usec, $sec) = explode(" ", microtime());    return ((float)$usec + (float)$sec);} //将下划线命名转换为驼峰式命名function convertUnderline1 ( $str , $ucfirst = true){    while(($pos = strpos($str , '_'))!==false)        $str = substr($str , 0 , $pos).ucfirst(substr($str , $pos+1));     return $ucfirst ? ucfirst($str) : $str;} //将下划线命名转换为驼峰式命名function convertUnderline2 ( $str , $ucfirst = true){    $str = explode('_' , $str);    foreach($str as $key=>$val)        $str[$key] = ucfirst($val);     if(!$ucfirst)        $str[0] = strtolower($str[0]);     return implode('' , $str);} //将下划线命名转换为驼峰式命名function convertUnderline3 ( $str , $ucfirst = true){    $str = ucwords(str_replace('_', ' ', $str));    $str = str_replace(' ','',lcfirst($str));     return $ucfirst ? ucfirst($str) : $str;} //将下划线命名转换为驼峰式命名function convertUnderline4 ( $str , $ucfirst = true){    $str = preg_replace('/_([A-Za-z])/e',"strtoupper('$1')",$str);    return $ucfirst ? ucfirst($str) : $str;} //将下划线命名转换为驼峰式命名function convertUnderline5 ( $str , $ucfirst = true){    $str = preg_replace_callback('/([-_]+([a-z]{1}))/i',function($matches){        return strtoupper($matches[2]);    },$str);    return $ucfirst ? ucfirst($str) : $str;} $counts = 100000;//第1种方式调用10w次所需时间$s1 = microtime_float();for ($i=0;$i<$counts;$i++){    $str= 'abcd_efgh_igk_lmn';    convertUnderline1($str);}$e1 = microtime_float();echo 'convertUnderline1: run time = ';echo $e1-$s1;echo '<br />'; //第2种方式调用10w次所需时间$s2 = microtime_float();for ($i=0;$i<$counts;$i++){    $str= 'abcd_efgh_igk_lmn';    convertUnderline2($str);}$e2 = microtime_float();echo 'convertUnderline2: run time = ';echo $e2-$s2;echo '<br />'; //第3种方式调用10w次所需时间$s2 = microtime_float();for ($i=0;$i<$counts;$i++){    $str= 'abcd_efgh_igk_lmn';    convertUnderline3($str);}$e2 = microtime_float();echo 'convertUnderline3: run time = ';echo $e2-$s2;echo '<br />'; //第4种方式调用10w次所需时间$s2 = microtime_float();for ($i=0;$i<$counts;$i++){    $str= 'abcd_efgh_igk_lmn';    convertUnderline4($str);}$e2 = microtime_float();echo 'convertUnderline4: run time = ';echo $e2-$s2;echo '<br />'; //第5种方式调用10w次所需时间$s2 = microtime_float();for ($i=0;$i<$counts;$i++){    $str= 'abcd_efgh_igk_lmn';    convertUnderline4($str);}$e2 = microtime_float();echo 'convertUnderline5: run time = ';echo $e2-$s2;echo '<br />';

经过测试发现，效率由高到低为   方法3>方法2>方法1>方法4>方法5  当然这是每个函数执行10w次才能看出的结果，当然1w次也能看出差别，1次就可以忽略不计了。
下面是测试结果：

执行1K次：
convertUnderline1: run time = 0.005000114440918
convertUnderline2: run time = 0.0040009021759033
convertUnderline3: run time = 0.0039999485015869
convertUnderline4: run time = 0.014001131057739
convertUnderline5: run time = 0.01600193977356

执行1w次：
convertUnderline1: run time = 0.056005954742432
convertUnderline2: run time = 0.033003091812134
convertUnderline3: run time = 0.028002977371216
convertUnderline4: run time = 0.14401507377625
convertUnderline5: run time = 0.13701295852661

执行10w次：
convertUnderline1: run time = 0.44704508781433
convertUnderline2: run time = 0.32203197479248
convertUnderline3: run time = 0.2670259475708
convertUnderline4: run time = 1.3601360321045
convertUnderline5: run time = 1.3231329917908