Using Expressions

To better understand how expressions and operators can be chained together to create more complex behaviors, follow the examples below.

For more information on the subject, see About Expressions and About Functions.

Calculator

To build a simple calculator, follow the procedure below.

Step	Action
1	Open your already existing application or start a new one.
2	Add two textboxes with a label in between. Change the name of the controls as follows: First textbox: `FirstNumber` Label: `+` Second texbox: `SecondNumber`
3	Add another label after the second textbox. Change the name to `Sum`.
4	Add the following expression to the `Sum` label: = `FirstNumber` + `SecondNumber`

After following the procedure above, the app will look as in the image below.

To build a simple input validation, follow the procedure below.

Step	Action
1	Open your already existing application or start a new one.
2	Create an app variable called `Number`.
3	Create a textbox that is value bound to the `Number` variable. Add the default text `0`.
4	Add a label with the following text: `This value is greater than or equal to 5!`.
5	Add the following expression: =`Number`<5

When the inserted number is lower than five, the validation label is hidden. After following the procedure above, the runtime should look like below:

To return the sum of a specified column of a table bound to Orchestrator output, follow the procedure below.

In this example we will retrieve the sum of a column called Age, containing the age of all people listed in the table.

Step	Action
1	Open your already existing application or start a new one.
2	Create a table with a column called Age.
3	Bound the table column to an Orchestrator output by selecting it in the Data Source property. In this example we will pick a source called `Out.out_datatable`.
4	Create a label and write `SUM(AGE):` in the Text property.
5	Create a second label right next to the first one and pick the `Sum` function and `out.datable.Age` from the Resources list.`=Sum(out_datatable.Age)` in the Text property.
6	Save the app and preview it.