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Subroutines
Subroutines have the same utility in ASP as it has in other languages.
In the next two examples, we have asked our visitors his name, and depending
on that answer a different response is sent to the client. The response will be
the same in both cases, but in the second one subroutines are used. The use of
subroutines may be very useful when there are a lot of instructions to be
perform within a subroutine. This way it will allow us to simplify the structure
of our script.
Example 1
<%
TheName=request.form("name)
if TheName="John" then
response.write ("Hi, John. How are you?")
response.write ("<br>Did you know I got married last month?")
else
response.write ("Hi. How are you?")
end if
%> |
Example 2
<%
TheName=request.form("name)
if TheName="John" then
ResponseToJohn()
else
ResponseToUnknown()
end if
Sub ResponseToJohn()
response.write ("Hi, John. How are you?")
response.write ("<br>Did you know I got married last month?")
End Sub
Sub ResponseToUnknown()
response.write ("Hi. How are you?")
End
Sub
%> |
In order to call a subroutine, we will use this kind of code:
Whatever()
Where Whatever is the name of the subroutine (it is recommended to use a very
descriptive name of the task we want to perform within the subroutine to make it
easier to understand the script). We may also provide information to the
subroutine in order to perform the specified task. The data will be provided
this way:
Whatever(data1, data2 ... dataN)
In the following example we will provide different data to a unique
subroutine depending on the Name of the person provided throw a form:
Example 3
<%
TheName=request.form("name)
if TheName="John" then
ResponseToVisitor(35,Sue,New York)
else
if TheName="Peter" then
ResponseToVisitor(33,Sally,Los Angeles)
else
response.write("Who are you?")
end if
end if
Sub ResponseToVisitor(AA,BB,CC)
response.write ("I know your are"
& AA & "years old, ")
response.write ("you are married to"
& BB & ", and")
response.write ("you are living in " & CC)
End Sub
%> |
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In line 14 it is specified AA is the first variable to be get, BB the second
one, and CC the third one. The values for the three variables are provided in
the same order in line 5 or line 8.
The example above also shows subroutines are very useful to avoid repeating a
specific number of tasks several times within the script, so that the script
looks more organized and it is smaller.
Include/virtual
Server Side includes or SSI is a very simple programing language (see a small
tutorial) but it also has a very
limited number of instructions. We will consider only one option SSI allows us
to use within our asp scripts: include/virtual.
In the next example we will use the include option of SSI in a our asp script
(response.asp). This command allows as to add a set of instructions from
different files (file1.txt and file2.txt bellow) and execute them.
Example 4
| response.asp |
<%
TheName=request.form("name)
if TheName="John" then
%>
<!--#include virtual="/file1.html" -->
<% else
%>
<!--#include virtual="/file2.asp" -->
<%
end if %> |
| File1.html |
Hi, John.<br>
I know your are 31 years old, you are married
to Sue, and you are living in New York. |
| File2.asp |
<%
for i=1 to 3
response.write(Thename &
"...<BR>")
next
response.write("Who are you?")
%> |
In this case, if the name of the person who is visiting our page is John,
then we will respond with file1.html. If not, then we will execute some asp
instructions from file2.asp.
The include file must be a text file (.txt, .html, .htm, .shtml, .asp...).
Although we have used file1.html and file2.asp, the script will work exactly in
the same way with file1.txt and file2.txt (changing the name of the files would
have no effect).
By using SSI and asp we may also get a secret page:
| secret_page.asp |
<%
UserName=request.form ("username")
Password=request.form("password")
if UserName="myusername" and
Password="mypassword" then
%>
<!--#include
virtual="/cgi-bin/secret_info.txt" -->
<% else %>
<Form Action=secretpage.asp method=post>
Username:
<input type=text name=username size=15><BR>
Password: <input type=text name=password
size=15><BR>
<input type=Submit Value=Send>
</form>
<% end if %> |
| secret_info.txt |
This is my secret information:<BR>
My name is
John.<BR>
My surname is Smith.<BR>
<BR>End of
secret information. |
In this case it is convenient to save secret_info.txt file in the cgi-bin
directory (the .txt file is not accessible by visitors from this directory, but
it will be accessible from our top directory).
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