Fundamentals of Numbers

Numeric literals do not require any enclosing punctuation. You can specify a number using any valid numeric characters. InterSystems IRIS evaluates a number as syntactically valid, then converts it to canonical form.

The syntactic requirements for a numeric literal are as follows:

It can contain the decimal numbers 0 through 9, and must contain at least one of these number characters. It can contain leading or trailing zeros. However, when InterSystems IRIS converts a number to canonical form it automatically removes leading integer zeros. Therefore, numbers for which leading integer zeros are significant must be input as strings. For example, United State postal Zip Codes can have a leading integer zero, such as 02142, and therefore must be handled as strings, not numbers.
It can contain any number of leading plus and minus signs in any sequence. However, a plus sign or minus sign cannot appear after any other character, except the “E” scientific notation character. In a numeric expression a sign after a non-sign character is evaluated as an addition or subtraction operation. In a numeric string a sign after a non-sign character is evaluated as a non-numeric character, terminating the number portion of the string.
InterSystems IRIS uses the PlusSign and MinusSign property values for the current locale to determine these sign characters (“+” and “-” by default); these sign characters are locale-dependent. To determine the PlusSign and MinusSign characters for your locale, invoke the GetFormatItem()Opens in a new tab method:
```
  WRITE ##class(%SYS.NLS.Format).GetFormatItem("PlusSign"),!
  WRITE ##class(%SYS.NLS.Format).GetFormatItem("MinusSign")
```
It can contain at most one decimal separator character. In a numeric expression a second decimal separator results in a <SYNTAX> error. In a numeric string a second decimal separator is evaluated as the first non-numeric character, terminating the number portion of the string. The decimal separator character may be the first character or the last character of the numeric expression. The choice of decimal separator character is locale-dependent: American format uses a period (.) as the decimal separator, which is the default. European format uses a comma (,) as the decimal separator. To determine the DecimalSeparator character for your locale, invoke the GetFormatItem()Opens in a new tab method:
```
  WRITE ##class(%SYS.NLS.Format).GetFormatItem("DecimalSeparator")
```
It can contain at most one letter “E” (or “e”) to specify a base-10 exponent for scientific notation. This scientific notation character (“E” or “e”) must be preceded by a integer or fractional number, and followed by an integer.

Numeric literal values do not support the following:

They cannot contain numeric group separators. These are locale-dependent: American format uses commas, European format uses periods. You can use the $INUMBER function to remove numeric group separators, and the $FNUMBER function to add numeric group separators.
They cannot contain currency symbols, hexadecimal letters, or other nonnumeric characters. They cannot contain blank spaces, except before or after arithmetic operators.
They cannot contain trailing plus or minus signs. However, the $FNUMBER function can display a number as a string with a trailing sign, and the $NUMBER function can take a string in this format and convert it to a number with a leading sign.
They cannot specify enclosing parentheses to represent a number as a negative number (a debit). However, the $FNUMBER function can display a negative number as a string with a enclosing parentheses, and the $NUMBER function can take a string in this format and convert it to a number with a leading negative sign.

A number or numeric expression can containing pairs of enclosing parentheses. These parentheses are not part of the number, but govern the precedence of operations. By default, InterSystems IRIS performs all operations in strict left-to-right order.

Canonical Form of Numbers