Questions about string truncation

Ask $ str = "sales" about string truncation ";
$ Str = "sales in large ";
$ Str = "basic sales acquisition principles ";
$ Str = "left blank ";

Echo substr ($ str, 1 );

Why is it garbled?
I found some solutions on the Internet http://www.111cn.net/phper/php-cy/35494.htm are not good, or show garbled. How can I solve this problem? my gbk code

Reply to discussion (solution)

Because substr cannot process unicode strings ......

Try mb_substr ()

It's still garbled.

Mb_internal_encoding ("GBK ");

Echo mb_substr ($ str, 1 );

The utf8 and gbk encoding methods for string truncation are different.

The webpage code must be consistent with the webpage content code.

$ Str = "basic sales acquisition principles ";
Echo mb_substr ($ str, 1,6, "gb2312 ");