Overview of evaluation scalar functions

Use evaluation scalar functions to evaluate an expression based on your records and return a result.

Functions that use evaluation scalar functions

You can use evaluation scalar functions with the Eval, Where, and Select streaming functions. See the following pages for more information, including examples of how evaluation scalar functions are used with these streaming functions:

• Eval
• Where
• Select

You can also use evaluation scalar functions with any function that has an argument that accepts expressions. For example, the Send to Splunk HTTP Event Collector sink function has an index argument that accepts expression<string> values. When configuring this index argument, you can specify an expression that uses evaluation scalar functions to resolve to a string value. For example, you can specify the following expression, which uses the map_get function to extract an index value from a map called attributes, and then uses the cast function to cast the extracted value to the string data type: cast(map_get(attributes, "index"), "string")

Using evaluation scalar functions

• All functions that accept strings can accept either a literal string or any field. 
• All functions that accept numbers can accept either literal numbers or any numeric field.

Specifying literal strings

For most evaluation scalar functions, when a string argument is expected you can specify either a literal string or a field. The literal string must be enclosed in double quotation marks. For example, if you have a field called name which contains the names of your servers, and you want to append the literal string server at the end of the name. You would specify this: name + "server".​

Nested functions

You can specify a function as an argument to another function.

In the following example, the cidrmatch function is used as the first argument in the if function.

... | eval isLocal=if(cidrmatch("123.132.32.0/25",ip), "local", "not local");

Operators

The following tables list the basic mathematical operations that you can use with the evaluation scalar functions. For these operations to work, the values need to be valid for the type of operation. For example, with the exception of addition, arithmetic operations might not produce valid results if the values are not numerical. When concatenating values, Splunk software reads the values as strings, regardless of the value.

Arithmetic operators

Operators	Action	Description
+	Addition	Accepts two numbers and produces a number.
-	Subtraction	Accepts two numbers and produces a number.
*	Multiplication	Accepts two numbers and produces a number.
/	Division	Accepts two numbers and produces a number.
%	Modulo	Accepts two numbers and produces a number.

Boolean operators

Operators	Action	Description
AND	Logical AND operator	Accepts two Boolean values and produces a Boolean.
OR	Logical OR operator	Accepts two Boolean values and produces a Boolean.
NOT	Logical NOT operator	Accepts one Boolean value and produces the inverse of the value.
XOR	Exclusive OR operator	Accepts two Boolean values and produces a Boolean.
IS NULL	NULL operator	Accepts a value and returns TRUE if the field value is NULL.
IS NOT NULL	NULL operator	Accepts a value and returns TRUE if the field value is not NULL.
<	Less than	Accepts two numbers and produces a Boolean.
>	Greater than	Accepts two numbers and produces a Boolean.
<=	Less than or equal to	Accepts two numbers or two strings and produces a Boolean.
>=	Greater than or equal to	Accepts two numbers and produces a Boolean.
!=	Not equal to	Accepts two numbers or two strings and produces a Boolean.
= or ==	Equal to	In expressions, the = and == operators are synonymous. These operators compare the value of right side and left side of the expression. Returns 1 (true) if the sides are equal. Returns 0 (false) if the sides are not equal.
LIKE	Text pattern matching operator	Accepts two strings. For example string LIKE pattern. The pattern operator supports literal text, a percent ( % ) character for a wildcard, and an underscore ( _ ) character for a single character match. For example, field LIKE "a%b_" matches any string starting with a, followed by anything, followed by b, followed by one character.
IN	Matching operator	Accepts a value and a list, and checks whether the value is in the list. The list can either be a list literal or a field containing a list. For example string IN (1, 2, 3) or string IN (list_field). Returns a Boolean.