Modify the Action Language for a Chart

Stateflow® charts in Simulink® models have an action language property that defines the syntax for state and transition actions. An icon in the lower-left corner of the chart canvas indicates the action language for the chart.

  • MATLAB® as the action language.

  • C as the action language.

You can change the action language of a chart in the Action Language box of the Chart properties dialog box. For more information, see Differences Between MATLAB and C as Action Language Syntax.

Change the Default Action Language

MATLAB is the default action language syntax for new Stateflow charts. To create a chart that uses C as the action language, enter:

sfnew -C

To change the default action language of new charts, use the sfpref function. For example, to set C as the action language for new charts, enter:

sfpref(ActionLanguage="C");

Auto Correction When Using MATLAB as the Action Language

Stateflow charts that use MATLAB as the action language automatically correct common C constructs to MATLAB syntax:

  • Increment and decrement operations such as a++ and a--. For example, a++ is changed to a = a+1.

  • Assignment operations such as a += b, a –= b, a *= b, and a /= b. For example, a += b is changed to a = a+b.

  • Evaluation operations such as a != b and !a. For example, a != b is changed to a ~= b.

  • Comment markers // and /* */ are changed to %.

To disable this preference, use the sfpref function:

sfpref(EnableLabelAutoCorrectionForMAL=false);

C to MATLAB Syntax Conversion

For nonempty charts, after you change the action language property from C to MATLAB, a notification appears at the top of the chart. The notification provides the option to convert some of the C syntax to MATLAB syntax. In the notification, click the link to have Stateflow convert syntax in the chart. C syntax constructs that are converted include:

  • Zero-based indexing.

  • Increment and decrement operations such as a++ and a--. For example, a++ is changed to a = a+1.

  • Assignment operations such as a += b, a –= b, a *= b, and a /= b. For example, a += b is changed to a = a+b.

  • Binary operations such as a %% b, a >> b, and a << b. For example, a %% b is changed to rem(a,b).

  • Bitwise operations such as a ^ b, a & b, and a | b. For example, if the chart property Enable C-bit operations is selected, then a ^ b is changed to bitxor(a,b).

  • C style comment markers. For example, // and /* */ are changed to %.

If the chart contains C constructs that cannot be converted to MATLAB, Stateflow shows a message in a dialog box. Click on the warnings link to display the warnings in the Diagnostic Viewer. Choose whether or not to continue with the conversion of supported syntax. C constructs not converted to MATLAB include:

  • Explicit type casts with cast and type

  • Operators such as &, * and :=

  • Custom data

  • Access to workspace variables using ml operator

  • Functions not supported in code generation

  • Hexadecimal and single precision notation

  • Context-sensitive constants

See Also

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