網(wǎng)上其實(shí)已經(jīng)有很多這種方法了，今天在thinkphp源碼中看到了他的實(shí)現(xiàn)，感覺還是很巧妙的，記錄一下

<?php

/**
 * 下劃線命名風(fēng)格轉(zhuǎn)換成駝峰命名風(fēng)格
 * @param $string
 * @param bool $ucfirst 轉(zhuǎn)換后首字母是否大寫
 * @return mixed|string
 */
function parseCamel($string, $ucfirst = false)
{
    //替換過程 name_style => _s => s => S => nameStyle
    $string = preg_replace_callback('/_([a-zA-Z])/', function ($match) {
        return strtoupper($match[1]);
    }, $string);

    return $ucfirst ? ucfirst($string) : $string;
}

/**
 * 駝峰命名風(fēng)格轉(zhuǎn)換成下劃線命名風(fēng)格
 * @param $string
 * @return string
 */
function parseUnderline($string)
{
    //替換過程 NameStyle => N | S => _N | _S => _Name_Style => Name_Style => name_style
    $string = strtolower(trim(preg_replace("/[A-Z]/", "_\\0", $string), "_"));

    return $string;
}

echo parseCamel('name_style') . "\n";                    //輸出 nameStyle
echo parseCamel('name_style', true) . "\n";       //輸出 NameStyle
echo parseUnderline('NameStyle') . "\n";                 //輸出 name_style