Pass a char to C file

I am using an embedded Matlab code for calling a C code, which read a text file. However I need to update the code below to pass a the text file name. I think I need to pass a char to the code, but I am not sure how to modify the c code below:

#include <stdio.h> 
#include <stdlib.h>
#include "readerext4.h"

void readerext4(int32_T size, real_T *txpos, real_T *typos, real_T *tzpos, real_T *tvxpos, real_T *tvypos, real_T *tvzpos)
{
    int32_T row;

  FILE *cfPtr;  // cfPtr = flowfield.dat file pointer
         FILE *cfPtrDebug;

  if ( cfPtr = fopen( "Flowfield.dat", "r" ))

          cfPtrDebug = fopen( "Debug.txt", "w" );
              {
      for ( row = 0; row < size; row++ )
      {
                      fscanf( cfPtr, "%lf", txpos+row);
                      fscanf( cfPtr, "%lf", typos+row);
                      fscanf( cfPtr, "%lf", tzpos+row);
                      fscanf( cfPtr, "%lf", tvxpos+row);
                      fscanf( cfPtr, "%lf", tvypos+row);
                      fscanf( cfPtr, "%lf", tvzpos+row);         
                      fprintf( cfPtrDebug, "%d\n", row + 1 );
                    }

  fclose( cfPtr );

      fclose( cfPtrDebug );
      }
  }

So instead of hard coding the the text file name (Flowfield.dat), I would like to pass a char (e.g. filename = flowfield.dat) to the C code. Can someone help, please? Thanks.

Answer 1

[Jan]

void readerext4(int32_T size, real_T *txpos, real_T *typos, real_T *tzpos,
                real_T *tvxpos, real_T *tvypos, real_T *tvzpos,
                const char* FileName)  /* added */
{ int32_T row;
  FILE *cfPtr; // cfPtr = flowfield.dat file pointer FILE *cfPtrDebug;
  if ( cfPtr = fopen(FileName, "r" ))

And append the "const char* FileName" in the header file also:

void readerext4(int32_T size, real_T *txpos, real_T *typos, real_T *tzpos,
                real_T *tvxpos, real_T *tvypos, real_T *tvzpos,
                const char* FileName);

[Sandeep]

Many thanks Jan. I tried creating a empty char array in Simulink, but Simulink do not support this. Any idea how to solve this problem? If I am right,Simullink do not accept a char!

[Jan]

I do not work with Simulink, but I'd expect, that it accepts mxChar, which is an UTF16 encoded character, or a uint16_T from the view of the compiler.

[Sandeep]

Thanks a lot Jan.