WWW based forms

Form items

The following form contains the majority of standard items supported by forms in HTML. To see how to create a form with these items simply look at the html source for this page. Note that not all of these may be supported by the browser you are using, for example, I can't find a browser that supports "scribbling" or the numeric-range input.

int main(int argc,char **argv)
{
   int c;

   printf("Content-type: text/html\n\n");
   printf("<pre>");
   while ((c = getchar()) != EOF) {
      if (c == '&')
         putchar('\n');
      else
         putchar(c);
   }
   printf("</pre>\n");
}

Perhaps the most common action to be taken on a form contents is to email the entered information to an email address. The following is the documentation (and example) of a C/C++ program I have written that deals with this. The form is given below to illustrate the features, as before look at the source to see how things are done.

• Fields are written to the email message along with their values. To make this more readable it is recommended that field names end in a colon. So for example a field as follows
  <input type=text name="Name:" value="">
  Will appear in the email message as
  Name: Paul Bourke

• Inserting documentation, titles, footers etc in the email that don't appear on the form is achieved by using hidden fields with names starting with "_Text:". For example
  <input type=hidden name="_Text:" value="A title for the email message">

• The cgi needs to know the email addresses to send the form data to. This is accomplished by including up to 2 email addresses as arguments to the cgi, each email address is separated by "&". For example
  <form action="emailform.cgi?pbourke@swin.edu.au" method="post">

• Some fields may need to be compulsary, while this can be achieved by javascript this cgi can also check fields that must filled in. Compulsory fields are indicated by their names which start with a "*". See the error file specification for the action taken on an missing compulsory field. For example
  <input type=text name="*Name:" maxlength=60 size=20 value="">

• It is generally convenient to have a specific subject set in the email. This is accomplished with a hidden field with the name "_Subject:". For example
  <input type=hidden name="_Subject:" value="Contents of WWW form">

• If there are no errors a file (normally formatted as html) is sent back to the browser. The name of this file is specified in a hidden field called "_OkFile:", for example
  <input type=hidden name="_OkFile:" value="allOK.html">
  A generic success message will be sent if this field doesn't exist.

• If there are some errors, eg: compulsory fields not supplied, then a file is sent back to the browser. The name of this file is specified in a hidden field called "_ErrorFile:", for example:
  <input type=hidden name="_ErrorFile:" value="error.html">
  A generic error message will be sent if this field doesn't exist.

• If a field with the name "Email:" is encountered then it is used as the "From" field of the email message....so replying to the email will work. For example:
  <input type=text name="Email:" size=30 value="">
  If the email field is compulsory then use the following
  <input type=text name="*Email:" size=30 value="">

• If an internal error message is generated then an informative message is displayed for the user to report to the site administrators. This is also useful for debugging problems.

• If you're running Apache with server side includes enabled then other globals can be included with the emails, for example the browser the person is using and the address of their machine.
  <input type=hidden name="Host:" value="<!--#echo var="REMOTE_HOST" -->">
  <input type=hidden name="Browser:" value="<!--#echo var="HTTP_USER_AGENT" -->">

Sample form

From: paul@bourke.gen.nz
Date: Sun Apr 13, 2003  4:32:50  PM Australia/Brisbane
Subject: Contents of WWW form
Reply-To: paul@bourke.gen.nz

A title for the email message
Host: launceston-atm.vic-remote.bigpond.net.au
Browser: Mozilla/5.0 (Macintosh; U; PPC Mac OS X; en) 
         AppleWebKit/60 (like Gecko) Safari/60
---
Name: Paul Bourke
Address: Here and there
Email: paul@bourke.gen.nz
Age group: Private
Cars: None
Car: Yes
Taxi: Yes
Comments: What a silly survey.
---
End of message