Use PHP to convert the underscore-delimited named string into camelCase naming, and change the first letter after the underscore to uppercase

The recent project uses the symfony framework. This framework uses ORM to operate the database in this team. To be honest, the development efficiency and operating efficiency of using ORM are not necessarily much higher, as far as its entity naming and existing database fields are concerned. The naming is different. The ORM entity attribute naming is in camel case, and the database fields are separated by underscores, which creates a field mapping process. When you encounter the need to manually write the array required by an entity, field mapping is a headache, especially when there are many fields, it will make you want to vomit. At this point, a problem arises, which is to convert the named fields separated by underscores into camelCase naming. I'm also very lazy. After searching online for a long time, I couldn't find a specific PHP Demo. Some of them are also written in Java and are quite complicated. So I took it upon myself to have enough food and clothing, and wrote two of them. Without further ado, I just posted the code:

<?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);
}

//第一种方式调用10w次所需时间
$s1 = microtime_float();
for ($i=0;$i<1000;$i++)
{
    $str= 'abcd_efgh_igk_lmn';
    convertUnderline1($str);
}
$e1 = microtime_float();
echo 'convertUnderline1: run time = ';
echo $e1-$s1;echo '<br />';

//第二种方式调用10w次所需时间
$s2 = microtime_float();
for ($i=0;$i<1000;$i++)
{
    $str= 'abcd_efgh_igk_lmn';
    convertUnderline2($str);
}
$e2 = microtime_float();
echo 'convertUnderline2: run time = ';
echo $e2-$s2;

Why should I write two of them? There are two different processing methods. I want to see which one is more efficient.
After testing, it was found that the method of string splicing is 0.1 seconds slower than using arrays. Of course, this is the result that can only be seen after executing each function 100,000 times. Of course, the difference can also be seen 10,000 times, and it can be ignored after 1 time. Forget it.
The following are the test results:
Executed 1K times:
convertUnderline1: run time = 0.0050010681152344
convertUnderline2: run time = 0.0039999485015869

Executed 1w times:
convertUnderline1: run time = 0.05500602722 168
convertUnderline2: run time = 0.036003828048706

Executed 10w times ：
convertUnderline1: run time = 0.46304702758789
convertUnderline2: run time = 0.31903195381165

Why is string interception and splicing slower than array concatenation? If you have seen the bottom layer of PHP C you will understand. So in the future, if there are a large number of strings that need to be concatenated into one string, do not use dot concatenation, put them in an array and use implode concatenation.

One more thing to say is that this method also works in JS, array connection is better than string connection block.

The above introduces how to use PHP to convert the underscore-delimited named string into camel case naming method, and change the first letter after the underscore to uppercase, including the following aspects. I hope it will be helpful to friends who are interested in PHP tutorials.