Lecture 6 - Applications #3.2: HTTP

URL Encoding

When form information is returned to the HTTP server, it is encoded into a format called (using MIME terminology):

application/x-www-form-urlencoded

...or simply "URL-encoded". In this format:

ASCII space characters (decimal 32) are (usually) replaced by the "+" character. This is a hangover from an older format and is normally, but not universally, used -- see next point.
Most (but not all) non-alphanumeric characters are encoded in hexadecimal format, thus: %HH, where the H characters are the two hexadecimal digits of the byte. Sometimes the space character is also sent in this format, as "%20", instead of as "+".
The fields of a form are encoded as name=value, with each name-value pair separated by the "&" (ampersand) character.
Fields with null values are (normally) not sent, nor are unselected CHECKBOXes and RADIO buttons.

Lecture 06: Applications #3.2: HTTP