Passing Parameters via CGI
You don’t need a form to pass a parameter to (most) CGI
programs. This feature is convenient because it lets programs be
called via simple links, not just by full-blown forms. To test this
out, take the original URL and add a question mark followed by the
parameter name, an equal sign, and the value desired. For example,
the following URL would call the ice_cream
script with the
flavor parameter set to the value
When you point your browser at this URL, the browser not only
requests the web server to invoke the
ice_cream.plx program, but it also passes the
flavor=mint to the program. Now it’s
up to the program to read the argument string and pick it apart.
Doing this properly is not as easy as you might think. Many programs
try to wing it and parse the request on their own, but most
hand-rolled algorithms only work some of the time. Given how hard it
is to get it right in all cases, you probably shouldn’t try to
write your own code, especially when perfectly fine modules already
handle the tricky parsing business for you.
Enter the CGI.pm module, which always parses the incoming CGI request correctly. To pull this module into your program, merely say:
somewhere near the top of your program.
statement is somewhat like a
#include statement in C programming in that it pulls in code from another file at compile time. But it also allows optional arguments specifying which ...