Detailed Documentation on Conditional (if/else/endif) Processing

This page is part of the WebCom Forms Processor Guide. This page describes in detail how to use if/else/endif in your form configuration file. This page describes in detail the syntax and rules for using if/else/endif. There is also an introductory page on if/else/endif.

The structure of an if/else/endif construct in the configuration file is as follows:

if (condition)

(statements)

else

(statements)

endif

• If (condition) is true, the statements between if and else (or endif if there is no else) are executed; if (condition) is false, only the statements between the else and the endif (if any) are executed.
• The else block is optional. You can have an if followed by a set of statements, followed simply by an endif.
• The condition of the if must be enclosed in parenthesis, and nothing should follow the closing parenthesis on an if line.
• The entire if condition must be on one line (but there is no limit on the length of the line).
• else (if used) and endif must be on separate lines by themselves.

The following operators are available for testing values (for use in the condition expression in the if statement):

Numeric test    String test     Meaning
    ==              eq          Equal to
    !=              ne          Not equal to
    >               gt          Greater than
    >=              ge          Greater than or equal to
    <               lt          Less than
    <=              le          Less than or equal to
    !               !           (Boolean) Not (!TRUE = FALSE/!FALSE=TRUE)
                                if (! ($order_amt >= 100)) is the same as
                                if ($order_amt < 100)

Note the distinction between testing string (alphabetical) values, and testing numeric values. (e.g. "50" comes after (is greater than) "456" alphabetically, but "50" is less than "456" numerically).

You can do complex comparisons using && (and) and || (or). && is evaluated before ||, but parenthesis can be used to override the order of operation.

Example:

if ($salary>30000 && $no_cars>3 || $salary > 60000)
format screen
Congratulations!  You qualify for a super-gold card with no annual fee!
.
endif

You can use and exclamation point (!) for "not":

if (!($salary>30000 && $no_cars>3 || $salary > 60000))
format screen
Congratulations!  You qualify for our layaway purchase plan!
.
endif

If you know how to use UNIX regular expressions, you can also check for pattern matches:

    =~   /pattern/[i]      Matches pattern [i = case insensitive]
    !~  /pattern/[i]       Does not match pattern

For example:

if ($phone_no !~ /\(\d\d\d\) \d\d\d-\d\d\d\d\)/)
format screen
<LI>Please enter your phone number in this format: (nnn) nnn-nnnn
.
endif

Regular expression patterns must be compatible with PERL regular expressions. Refer to the PERL Home Page for additional resources for learning about about PERL regular expressions (Programming Perl [Nutshell Handbook], Larry Wall [Editor], et al; O'Reilly & Associates; ISBN: 1565921496 is probably the best resource).

Note that you can create new parameters and set their values (see the Forms Processor parameter introduction page). You can use conditional processing to set various parameters you define and then take certain actions based on the values of your parameters. This helps alleviate the limitation of no nested ifs, and can be used to create very intelligent forms.

PLEASE NOTE: When setting parameter values to literal values, quotes are optional ($email=me@webcom.com). However: quotes are required for literal values in conditional tests! (e.g., if ($email eq "me@webcom.com") ). If this is confusing to you, just remember this rule: always surround literal string values with double quotes, and you'll be fine.

An example of using a custom parameter with if/else/endif can be seen on the if/else/endif introductory page.

As well as comparing field values and literal values with comparison operators and patterns, you can compare with the return value of the following functions:

• substr(value,start,length) - returns length characters of value (a field or literal value) starting at position start (where the first position of a string is numbered zero, and the last position is the length of the string minus 1).
• index(string1,string2) - returns the position (where zero is the first character) of the first occurrence of string2 within string1 (rindex returns the last occurrence).
• int(number) - returns the integer portion of a number (removes any fractional portion).
• ord(string) - returns the ASCII code of the first position of the string
• length(string) - returns the length of the string
• -e "filename" (or -e $filename) - returns TRUE if the file exists, and FALSE if it does not (filename can be a literal filename in quotes, or a field name or parameter prefixed by a dollar sign, e.g. $filename). The filename must be relative to your home directory, so (-e download/index.txt) checks for the existence of the file index.txt in the download subdirectory of your home directory. Any of the PERL file test switches can be used in this manner (-d to check if a file is a directory, -T to check whether a file is a text file, etc.).

For more info on the use of these commands you can see our Advanced Commands section.