mb_strpos() returns the numeric position of the first occurrence of needle in the haystack string. If needle is not found, it returns FALSE.
mb_strpos() performs multi-byte safe strpos() operation based on number of characters. needle position is counted from the beginning of the haystack. First character's position is 0. Second character position is 1, and so on.
offset is search offset. If it is not specified, 0 is used.
encoding is character encoding name. If it is omitted, internal character encoding is used.