$a[]="a1";
$a[]="a2";
$a[]="a3";
print_r($a);
unset($a[1]);
print_r($a);
		

implode(separator,array)

		
<?php
$arr = array('Hello','World!');
echo implode(" ",$arr);
?>
		
		

explode(separator,string,limit)

		
<?php
$str = "Hello world!";
print_r (explode(" ",$str));
?>
		
		

$str = iconv('UTF-8', 'GB2312', unescape(isset($_GET['str'])? $_GET['str']:''));
报错：iconv() : Detected an illegal character in input string		
		
//TRANSLIT 会自动将不能直接转化的字符变成一个或多个近似的字符，
//IGNORE 会忽略掉不能转化的字符，而默认效果是从第一个非法字符截断。

$str = iconv('UTF-8', 'GBK//IGNORE', unescape(isset($_GET['str'])? $_GET['str']:''));	
		

替代方案

$content = iconv("GBK", "UTF-8", $content);
$content = mb_convert_encoding($content, "UTF-8", "GBK");