How to reference variables and functions in JMeter

While writing test plans in JMeter, you will need to use many variables to store some values like command line arguments, random values etc. and different functions to perform different operations.

Referencing variables:
In JMeter, variables are referenced with curly braces and $(dollar sign) i.e. a variable with name var will be referenced as ${var}.

Function in Apache JMeter

JMeter functions are no different from normal languages like C, C++, Perl etc. These functions take some parameters and return some value after processing those arguments. By convention, JMeter function names always starts with '__' i.e. two underscores. 

A typical function call looks like: