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Subroutines and functions,

You use subroutines and functions for program-code that you need more then once in 1 script. You only need to write the code once, but you can use it several times. You can also get functions from outside the script. Then you get 1 function that you use on more pages.

Subroutines and function do both calculations both only functions return a value.

Subroutines

SUB subroutinename(parameters)
  instructions
END SUB

To call the subroutine 

CALL subroutinename(parameters)

Example(c11.asp):

<% @language=vbscript %>
<% response.buffer=true %>
<HTML>
<HEAD><TITLE>Example subroutines</TITLE></HEAD>
<BODY>

<%
if request.form("entry")="" then
  response.write("<form action=c11.asp method=post>")
  response.write("Give the side of a square <input type=text size=3 name:entry>")
  response.write("<input type=submit value=calculate>")
  response.write("</form>")
else
  response.write("<h2>Square</h2>")
  response.write("The surface is: ")
  call surfacesquare(request.form("entry"))
end if
%>

</BODY>
</HTML>

<SCRIPT language=vbscript runat=server>
Sub surfacesquare(side)
  response.write(side*side)
end sub
</script>

As you can see this code combines 2 pages in 1. One who ask to user to enter something and another that gives the result.

 

Function 

FUNCTION functionname(parameters)
  instructions
  functionname=calculation
END FUNCTION

The function returns a value by giving a value to the functionname.

Example:

<% @language=vbscript %>
<HTML>
<HEAD><TITLE>Example function</TITLE></HEAD>
<BODY>

<%
if request.form("entry")=" " then
  response.write("<form action=c11.asp method=post>")
  response.write("Give the side of the square <input type=text size=3 name=entry><br>")
  response.write("<input type=submit value=calculate>")
  response.write("</form>")
else
  response.write("<H2>square</H2>")
  response.write("The surface is: ")
  response.write("surfacesquare(request.form("entry")))
end if
%>

</BODY>
</HTML>

<script language=vbscript runat=server>
FUNCTION surfacesquare(side)
  surfacesquare=side*side
END FUNCTION
</script>

 

Local and global variables

Local variables

The variables you create in a subroutine or a function are local variables. They are only known inside the function or subroutine.

Example:

SUB subroutine1
  DIM counter
  counter=5
END SUB

SUB subroutine2
  DIM counter
  counter=8
END SUB

You can use the same variable name in different sub-functions without conflicts.

Global variables

Variables created in the script, can be used in subroutines.

Example:

<% @language=vbscript %>
<HTML>
<HEAD><TITLE>Example Global variables</TITLE></HEAD>
<BODY>

<%
DIM strglobal
strglobal="The global variable"
response.write(strglobal)

SUB subroutine1
  DIM counter
  counter=5
  response.write(counter)
  response.write("<P>"& strglobal &"</P>")
END SUB

SUB subroutine2
  DIM counter
  counter=8
  response.write(counter)
  response.write("<P>"& strglobal &"</P>")
END SUB
%>

<P>Subroutine 1 ...<%subroutine1()%>
<P>Subroutine 2 ...<%subroutine2()%>
<P>Subroutine 1 ...<%subroutine1()%>

</BODY>
</HTML>

 

Public and private variables

1 ASP-page can have more then 1 script.

Private variables are only known in the script they are defined. They are defined with the word PRIVATE instead of DIM.
PRIVATE strtext

Public variables are also know outside the script they are defined. They are defined with the word PUBLIC instead of DIM.
PUBLIC strtext

 

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