lcfirst()

(PHP 5 >= 5.3.0, PHP 7)

使一个字符串的第一个字符小写

说明

lcfirst(string $str) : string

返回第一个字母小写的$str，如果是字母的话。

需要注意的是“字母”是由当前语言区域决定的。比如，在默认的“C”区域像日耳曼语系中的元音变音a (ä)将不会被转换。

参数

$str

输入的字符串。

返回值

返回转换后的字符串。

范例

Example #1lcfirst()例子：

<?php
$foo = 'HelloWorld';
$foo = lcfirst($foo);             // helloWorld
$bar = 'HELLO WORLD!';
$bar = lcfirst($bar);             // hELLO WORLD!
$bar = lcfirst(strtoupper($bar)); // hELLO WORLD!
?>

参见

• ucfirst()将字符串的首字母转换为大写
• strtolower()将字符串转化为小写
• strtoupper()将字符串转化为大写
• ucwords()将字符串中每个单词的首字母转换为大写

Easiest work-around I've found for <5.3:
<?php
$string = "CamelCase"
$string{0} = strtolower($string{0})
echo $string; // outputs camelCase
?>

A slight modification from Northie's post here ( http://us2.php.net/manual/en/function.ucfirst.php#68443), where lcfirst may not exist in your PHP build:
<?php
if(false === function_exists('lcfirst'))
{
  /**
   * Make a string's first character lowercase
   *
   * @param string $str
   * @return string the resulting string.
   */
  function lcfirst( $str ) {
    $str[0] = strtolower($str[0]);
    return (string)$str;
  }
}
/* Tests */
echo var_dump(lcFirst(NULL)).'<br />';  /* string(0) "" */
echo var_dump(lcFirst('')) .'<br />';  /* string(0) "" */
echo var_dump(lcFirst('S')) .'<br />';  /* string(1) "S" */
echo var_dump(lcFirst('É')) .'<br />';  /* string(0) "�" */
echo var_dump(lcFirst('Hello World!!!')); /* string(14) "hello World!!!" */

In some cases maybe more useful?
 $lower = strtolower( substr($upper,0,1) ) . substr($upper,1);

As of PHP release 6 direct reference modification is not permitted any more. 
Reference modification is the process of manipulating characters within a string by means of the instruction such as:
$str[0] in the code line: $str[0] = strtolower($str[0]);
For this reason I have recoded the lcfirst function (on function_exists('lcfirst') === false) as follows:
<?php
if ( false === function_exists('lcfirst') ):
  function lcfirst( $str ) 
  { return (string)(strtolower(substr($str,0,1)).substr($str,1));}
endif;
?>
Remarks:
Also notice that I have used the more modern scope delimeters (if:-endif;) and I have also removed the unnecessary intermediate result. That is, the manipulation is returned directly.