使用iconv（）檢查無效的UTF-8字符：檢測到輸入字符串中的非法字符

Question

我使用iconv（）檢查字符串是否包含無效的UTF-8字符。

$valid = $string == iconv('UTF-8', 'UTF-8//IGNORE', $string); 

然而，這仍然引發錯誤：「的iconv（）：檢測到輸入字符串非法字符」

就我這方面的知識不應該使用//忽略標誌是可能的嗎？

我使用的是在Ubuntu 14.04.1 LTS PHP 5.5.9-1ubuntu4.6

Answer 1

Another answer提供爲什麼iconv()拋出一個錯誤一個更好的答案：在PHP

The output character set (the second parameter) should be different from the input character set (first param). If they are the same, then if there are illegal UTF-8 characters in the string, iconv will reject them as being illegal according to the input character set.

Taken from a comment手冊，可以檢測是否字符串在UTF-8編碼與此功能：

$valid = mb_detect_encoding($str, 'UTF-8', true); // returns boolean. 

更多info on mb_detect_encoding();