URL Encoding

When you send form information with method="get", the information from the form is put into string form and appended to the CGI script’s URL. This means that the string can contain only characters that are valid in a URL. Blanks and certain punctuation such as question marks, commas, number signs, etc. cannot appear in a URL.

To get around this problem, the browser collects the form information, and then URL encodes the string before sending it off to the server as part of the URL. Blanks are converted to plus signs (which are legal), and any other non-valid characters are converted to a percent sign followed by the two-digit hexadecimal equivalent. For example, a comma is converted to %2C and a number sign is converted to %23.

Example

Let’s say your form has a field called poetName, and the user has typed Alfred, Lord Tennyson into that field. Another field is nPoems and the user has typed 20 into that field.

Collect information from first field; string is now:

poetName=Alfred, Lord Tennyson

Append information from second field

poetName=Alfred, Lord Tennyson&nPoems=20

URL-Encode the string

poetName=Alfred%2C+Lord+Tennyson&nPoems=20