Creating a Case Structure to Execute Conditional Code

1. Add a Case structure to the block diagram.

   Case structures are located on the Functions » Programming » Structures palette.

2. Wire an input value of a supported data type to the case selector ().

   The data the Case structure receives at the case selector determines which subdiagram executes. A subdiagram executes when the data at the case selector matches a selector label.

   You can position the case selector anywhere on the left border of the Case structure.

   Wire different data types to the case selector. The selector label values and the number of subdiagrams you can use depend on the data type, as shown in the table.

   Table 26. Valid Subdiagrams for Case Structure Data Types

   Supported Data Type	Subdiagrams of Case Structure
   Boolean	The structure has a True case and a False case.
   Error cluster	By default, the structure has an Error case and a No Error case. You can also use an error cluster to handle specific errors by their numeric error code with a Case structure.
   Integer String Enumerated type	User-defined. The structure can have any number of cases.

   Tip You can convert a tunnel to the case selector. To do so, right-click the tunnel and select Replace with Case Selector. If the previous case selector is wired, LabVIEW converts the previously wired case selector to a tunnel. You can also use the Replace With Case Selector method to convert a tunnel to the case selector programmatically.
3. Add objects inside the Case structure to build subdiagrams that the Case structure can execute.

   If necessary, you can add or duplicate subdiagrams.

   Tip You can specify a default subdiagram for case structures to avoid needing to create a unique subdiagram for every possible input.
4. For each case, use the Labeling tool to enter a single value or lists and ranges of values in the selector label at the top of the Case structure.

   In a given selector label, you can either enter a single value or span multiple values as follows.

   Option	Description
   Bounded range	Specify a range of values with both an upper bound and a lower bound. Syntax: .. between values. Example: x..z
   Open-ended range	Specify a range of values with either an upper bound or a lower bound. Syntax: .. before or after a value. Example: ..x or x..
   List	Specify discontinuous values or multiple sets of values. Syntax: , between values. Example: x, z

   You can combine lists and ranges in the same selector label.

   Tip Using Enter on the keyboard can input a line break in some contexts. To reliably accept data instead, use Enter on the number pad or the Enter Text button ().

   Note The behavior of values and ranges differs based on the data type that you wire to the case selector. For details about the values you can enter and their behavior, refer to Case Selector Label Behavior by Input Data Type.
   The value you enter in each selector label executes specific subdiagrams that correspond with the input value you pass to the structure.

   If you enter a selector label value that is not the same type as the object wired to the case selector, the value appears red. This indicates that the VI will not run. To fix the issue, delete the subdiagram or edit the value to a valid value.

Case Structure Example

For an example of using Case structures, refer to the Case Structure - Selector Data Types VI in the labview\examples\Structures directory.