Php core technology-supplement string functions

Form verification-verify user data (from the browser, get, post ). The javascript and php regular expressions are used for joint processing. String functions: a small number of common strings are processed by string processing functions in bytes. Gbk encoding: one Chinese character occupies 2 bytes. Utf8 encoding: one Chinese character occupies 3 bytes. Strlen (); length Substr (string, start position, truncation length): the truncation string is processed according to characters. For example, javascript strings are processed by characters. Php does not support character processing by default. you need to use php's multi-byte character extension. In Php. ini: Mb_strlen (); Mb_substr (); regular expressions: Batch string processing, regular expressions. Check whether the data entered by the user is in the email address? Whether a string rule is met. Common use of regular expressions: form verification-user data verification (from the browser data, get, post ). The javascript and php regular expressions are used for joint processing.