Returns the length of the initial portion of str1 which consists only of characters that are part of str2. The search does not include the terminating null-characters of either strings, but ends there. 检索字符串 dest 中第一个不在字符串 src 中出现的字符下标。返回 dest 所指向的空终止字节串的最大起...
Returns a pointer to the first occurrence of str2 in str1, or a null pointer if str2 is not part of str1. 查找 substr 所指的空终止字节字符串在 str 所指的空终止字节字符串中的首次出现。不比较空终止字符。
(PHP 4 >= 4.4.3, PHP 5 >= 5.1.3, PHP 7) mb_check_encoding — Check if the string is valid for the specified encoding mb_check_encoding — 检查字符串在指定的编码里是否有效