PHP替换，只替换匹配到的第一个

function str_replace_limit($search, $replace, $subject, $limit=-1) {

if (is_array($search)) {
foreach ($search as $k=>$v) {
$search[$k] = '`' . preg_quote($search[$k],'`') . '`';
}
}
else {
$search = '`' . preg_quote($search,'`') . '`';
}

return preg_replace($search, $replace, $subject, $limit);
}