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This example shows how to call a generated C library function from C code. It uses the C static library function absval described in Call a C/C++ Static Library Function from MATLAB Code.

1. Write a main function in C that does the following:

   • Includes the generated header file, which contains the function prototypes for the library function.

   • Calls the initialize function before calling the library function for the first time.

   • Calls the terminate function after calling the library function for the last time.

   Here is an example of a C main function that calls the library function absval:

   /*
   ** main.c
   */
   #include <stdio.h>
   #include <stdlib.h>
   #include "absval.h"
   
   int main(int argc, char *argv[])
   {
       absval_initialize();
       
       printf("absval(-2.75)=%g\n", absval(-2.75));
       
       absval_terminate();
       
       return 0;
   }
   

2. Configure your target to integrate this custom C main function with your generated code, as described in Specify External File Locations.

   For example, you can define a configuration object that points to the custom C code:

   1. Create a configuration object. At the MATLAB^® prompt, enter:

      cfg = coder.config('exe');

   2. Set custom code properties on the configuration object, as in these example commands:

      cfg.CustomSource = 'main.c';
      cfg.CustomInclude = 'c:\myfiles';

3. Generate the C executable. Use the -args option to specify that the input is a real, scalar double. At the MATLAB prompt, enter:

   codegen -config cfg  absval -args {0}

4. Call the executable. For example:

   absval(-2.75)