# Syntax of expressions in the blocks

To declare variables and set certain values ​​for them, the “[Variable Initialization](/en/studio/programming-visual/blocks.md#variableinit)” block is used.

!["Variable Initialization" block](/files/-M51qy1lrvlast0f4s2z)

For mathematical expressions — "[Expression](/en/studio/programming-visual/blocks.md#expression)" block.

!["Expression" block](/files/-M51s0-8mn_MW1mdTryJ)

Also, mathematical expressions, including those that change the values ​​of variables, can be used almost everywhere where you can specify a value.

Blocks and their properties that do not allow the use of mathematical expressions are described in the section ["Common blocks"](/en/studio/programming-visual/blocks.md#list-of-common-blocks).

All variables in the program are global, i.e. their values ​​can be used in any block in the program.

## TRIK Studio language

The language used inside the blocks is based on [Lua 5.3](https://www.lua.org/) and largely follows its syntax. Nevertheless, there are significant differences, so a full description of the language used in TRIK Studio is given here.

* [Types](/en/studio/programming-visual/expression-syntax/types.md)
* [Tokens](/en/studio/programming-visual/expression-syntax/lexemes.md)
* [Operators](/en/studio/programming-visual/expression-syntax/operators.md)
* [Sensor variables](/en/studio/programming-visual/expression-syntax/sensory-variables.md)
* [Constants](/en/studio/programming-visual/expression-syntax/const.md)
* [Built-in functions](/en/studio/programming-visual/expression-syntax/built-in-functions.md)

## Examples of expressions

Declaration of several variables in one block "[Expression](/en/studio/programming-visual/blocks.md#expression)":

![](/files/-MSi8prlEwpC9EOocyTZ)

The same using ["Variables Initialization" ](/en/studio/programming-visual/blocks.md#variableinit)blocks:

![](/files/-MSi8t4nF2w9Xgt8Aoxo)

Proportional controller for driving along the line using two light sensors for the TRIK platform:

![](/files/-MSi8wQewpjfPlGnAkFc)

An example of using [arrays](/en/studio/programming-visual/expression-syntax/types/array.md) to set the ports of the “Motors forward” block. An array is created with the name `a`, the port `M3` is assigned to the zero element, the first is `M1`, then the contents of the first element of the array are changed to M4, then the resulting array is transferred to the “Ports” property of the “Motors forward” block:

![](/files/-MSi8zGGBZbIYvXgIY0b)


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