php 将字符串中 中文替换

$str = "我是chinese,龙的传人!";
//匹配任意中文字符的表达式
$pattern = "/[\x7f-\xff]/sim";
$replacement = '';
//用该表达式替换，将替换掉字符串中出现的任意中文字符，包括中文符号。
echo 'Result:'.preg_replace($pattern, $replacement, $str);
//结果为：chinese,!

<?php
$test = "我是chinese,sdgwping";
$len = strlen($test);
$str = '';
$en = array("a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z");
for($i=0;$i<$len;$i++){
if(in_array($test[$i],$en)){
$str .= $test[$i];
}
}
echo $str;
?>
这段代码可以把英文字符提取出来，如果你需要提取其他的字符，可以添加到那个en数组里

代码如下：
$str="我是chinese";