CALC

Edit online

Evaluates a simple mathematical expression.

Type

Dialog Language function

Format

CALC(expression varname)
expression
A string containing the expression to be evaluated. Only integers and the operators listed below in ascending precedence are valid:
+
Addition
-
Subtraction
*
Multiplication
/
Integer division (result)
%
Modulo division (remainder)
-
Unary minus (same symbol as subtraction)

Parentheses can be used to group terms to alter the order of evaluation.

varname
The name of a variable to be updated with the result of the calculation. If the calculation cannot be performed, the variable is not updated.

Return Codes

0
expression was evaluated, and the result is in varname.
4

expression or varname was omitted or there is a syntax error in expression. Ensure that the CALC arguments are not null and that expression contains a valid mathematical formula.

8
Numeric overflow. Numbers and the results of calculations must be between -2,147,483,648 and 2,147,483,647, inclusive. It may be possible to reorder the calculations in your expression to eliminate an intermediate calculation overflow.
12
Stack overflow. The expression is too complicated to be evaluated. For example, it contains too many levels of parentheses. Reduce the number of parenthetical expressions.

Usage Notes®

  1. Only numbers are allowed. Any expression must be numeric. However, you can use variables in the string to be calculated: 
    set A 1
set B 8
set rc (calc('&A+&B' Result))

    The Dialog Manager evaluates the contents of the variables A and B before it builds the string that is passed to CALC. The result is '1+8', which can be processed correctly.

  2. Enclose expression in single quotation marks to prevent tokenization and truncation to 8 characters.
  3. CALC can handle a maximum negative value of -2,147,483,648. However, you cannot specify the value directly in expression because CALC treats the leading minus sign as a unary operator against the positive value 2,147,483,648, which is too large. To use the maximum negative value in a calculation, code it as follows: 
    (-2147483647 - 1)
  4. Division or modulo by 0 results in RC=8, numeric overflow.

Example

The following example builds a simple calculator:
)option level(1) popup
)declare
Exp scope(local) * expression string
Msg scope(local) * results message
RC scope(local) * return code from CALC
Result scope(local) * evaluation result
)init
set Exp 0 /* init exp string */
)prologue
set rc (calc('&Exp' Result))
if &RC = 0 set Msg 'Result is &Result'
else if &RC = 4 set Msg 'Syntax error in expression'
else if &RC = 8 set Msg 'Numeric overflow'
else set Msg 'Stack overflow'
)body
# SIMPLE CALCULATOR
#
#Enter expression:_Exp #
#
#&Msg
)epilogue
if &Syskey = ENTER reshow /* do it again */