4D Doc Center : Num

4D v13.4

Num


Num ( expression {; separator} ) -> Function result

Parameter	Type	Description
expression	String, Boolean, Longint	String for which to return the numeric form, or Boolean to return 0 or 1, or Numeric expression
separator	String	Decimal separator
Function result	Longint	Numeric form of the expression parameter

Description

The Num command returns the numeric form of the String, Boolean or numeric expression you pass in expression. The optional separator parameter designates a decimal separator for evaluating string type expressions.

String Expressions
If expression consists only of one or more alphabetic characters, Num returns a zero. If expression includes alphabetic and numeric characters, the command ignores the alphabetic characters. Thus, it transforms the string "a1b2c3" into the number 123.

There are three reserved characters that Num treats specially: the decimal separator as defined in the system (if the separator parameter is not passed), the hyphen “-”, and “e” or “E”. These characters are interpreted as numeric format characters.

The decimal separator is interpreted as a decimal place and must appear embedded in a numeric string. By default, the command uses the decimal separator set by the operating system. You can modify this character using the separator parameter (see below).
The hyphen causes the number or exponent to be negative. The hyphen must appear before any negative numeric characters or after the “e” for an exponent. Except for the “e” character, if a hyphen is embedded in a numeric string, the portion of the string after the hyphen is ignored. For example, Num("123-456") returns 123, but Num("-9") returns -9.
The e or E causes any numeric characters to its right to be interpreted as the power of an exponent. The “e” must be embedded in a numeric string. Thus, Num("123e–2") returns 1.23.
Note that when the string includes more than one "e", conversion might give different results under Mac OS and under Windows.

The separator parameter designates a custom decimal separator for evaluating the expression. When the string to be evaluated is expressed with a decimal separator different from the system operator, the command returns an incorrect result. The separator parameter can be used in this case to obtain a correct evaluation. When this parameter is passed, the command does not take the system decimal separator into account. You can pass one or more characters.

Note: The GET SYSTEM FORMAT command can be used to find out the current decimal separator as well as several other regional system parameters.

Boolean Expressions
If you pass a Boolean expression, Num returns 1 if the expression is True; otherwise, it returns 0 (zero).

Numeric Expressions
If you pass a numeric expression in the expression parameter, Num returns the value passed in the expression parameter as is. This can be useful more particularly in the case of generic programming using pointers.

Example 1

The following example illustrates how Num works when passed a string argument. Each line assigns a number to the vResult variable. The comments describe the results:

 vResult:=Num("ABCD") ` vResult gets 0

 vResult:=Num("A1B2C3") ` vResult gets 123

 vResult:=Num("123") ` vResult gets 123

 vResult:=Num("123.4") ` vResult gets 123.4

 vResult:=Num("–123") ` vResult gets –123

 vResult:=Num("–123e2") ` vResult gets –12300

Example 2

Here, [Client]Debt is compared with $1000. The Num command applied to these comparisons returns 1 or 0. Multiplying 1 or 0 with a string repeats the string once or returns the empty string. As a result, [Client]Risk gets either “Good” or “Bad”:

  ` If client owes less than 1000, a good risk.

  ` If client owes more than 1000, a bad risk.

 [Client]Risk:=("Good"*Num([Client]Debt<1000))+("Bad"*Num([Client]Debt>=1000))

Example 3

This example compares the results obtained depending on the “current” separator:

 $thestring:="33,333.33"

 $thenum:=Num($thestring)

  ` by default, $thenum equals 33,33333 on a French system

 $thenum:=Num($thestring;".")

  ` $thenum will be correctly evaluated regardless of the system;

  ` for example, 33 333,33 on a French system