Name C Structure Type to Use with Global Structure Variable

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This example shows how to name the C structure type to use in code generated for a global structure at the command line.

To name the C structure type to use for a structure variable, you use coder.cstructname. However, you cannot apply coder.cstructname directly to a global variable inside a function. Instead, use coder.cstructname to create a type object that names the C structure type. When you run codegen, specify that the global variable has that type. You can also use this approach to name the C structure type for a global cell array.

Alternatively, you can name the C structure type of a global structure variable by using the MATLAB® Coder™ app. In the app, after you define a global structure variable, click the Type Name button in the variable definition and enter the C structure type name. See Define Global Variables in the MATLAB Coder App.

Write a MATLAB Function That Uses a Global Variable

Write a MATLAB® function named getmyfield that returns field f1, which is a field of global structure variable g.

type getmyfield
function y = getmyfield %#codegen
global g;
y = g.f1;
end

Specify the C Structure Type Name

Define and initialize the global structure g. Then, use coder.cstructname to create a type object named T that has the properties of g and names the generated C structure type myStructType. 

global g
g = struct("f1",5)
g = struct with fields:
    f1: 5


T = coder.cstructname(g,"myStructType")
T = 
coder.StructType
   1×1 myStructType struct
      f1: 1×1 double

    Edit Type Object

Generate Code Using the C Structure Type

Generate code for getmyfield, specifying that g is a global variable with the type T. Inspect the C structure type definition in the generated code. The name of the generated C structure type is myStructType.

codegen -config:lib -globals {"g",T} getmyfield
Code generation successful.

file = fullfile("codegen","lib","getmyfield","getmyfield_types.h");
coder.example.extractLines(file,"/* Type Definitions */","#endif",1,1)
/* Type Definitions */
#ifndef typedef_myStructType
#define typedef_myStructType
typedef struct {
  double f1;
} myStructType;
#endif /* typedef_myStructType */

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