Query string

A query string is the part of a URL that conveys parametric data to the server.

Syntax

The basic syntax is ?parameter₁=value₁&parameter₂=value₂ . . .

• The query string starts with a question mark.
• Then follows a series of parameter=value pairs. For example, Message=hello.
• The parameter-value pairs are each separated by an equal sign.
• The series of pairs is separated by the ampersand, '&'.

URL Encoding

Spaces, ampersands, equal signs, and many other characters could cause trouble with the URL and the query string. Therefore the value in each parameter-value pair is URL-Encoded. This is a process by which each of these troublesome characters is converted into a numeric represenctation.

'%2D' is one such example.

• The percent sign signals the start of such a string.
• '2D' is the number 45 in HEX - in ASCII and UNICODE, each character has a numerical index.

Therefore, %2D is the minus sign, and %25 is the percent character.

Quirks

• Spaces are converted to plus signs, e.g. "hello there" would be converted to "hello+there".

See also

Email Attachments