String class not recognized in S-function

I want to use an S-function in my simulink model to convert a constant integer to a string, using ASCII code also. The digits of the number will be assigned in the following way: (0-> 'A',...,9->'J') Ex.

input 123 -> S-function -> output 'BCD'. Basically, i would like the same thing as him http://www.mathworks.com/matlabcentral/answers/1804-ascii-string-with-sci-transmit

I'm using S-function builder. The code below is put in the Output pane

typedef unsigned char byte;

byte i,nr;
byte v[10];
char w[10];
char s; //sign of the input number
string Convert(u[0]); //the function which does the conversion
{
  long newu = 0;
  nr = 0;
  s = 0;
  if(u[0]<0)
    s = 1;

while(u[0]!=0)
  {
    newu = newu * 10 + (u[0] % 10);
    u[0]/=10;
    nr++;
  }

for(i=nr;i>=1;i--)
  {
    v[i]=newu %10;
    newu/=10;
  }
  
for(i=1;i<=nr;i++)
  {
    switch(v[i])
    {
      case 0: w[i]='A';
        break;

                        case 1: w[i]='B';
        break;
                  case 2: w[i]='C';
        break;
             case 3: w[i]='D';
        break;
                        case 4: w[i]='E';
        break;
      case 5: w[i]='F';
        break;
                        case 6: w[i]='G';
        break;
      case 7: w[i]='H';
        break;
                        case 8: w[i]='I';
        break;
      case 9: w[i]='J';
        break;
    }
  }
string Convert[0](w); // converts char array(w) into a string
return(Convert[0]);
}
In the Library pane, i include the following:
#include <string.h>, but after build, i get ''undeclared identifier `string'''

I don't know about the errors in the code(i'm sure there are many, because i have little c knowledge)

Answer 1

[Walter Roberson]

The only type that <string.h> defines is size_t . See http://pubs.opengroup.org/onlinepubs/7908799/xsh/string.h.html

You might perhaps be thinking of C++'s <string;> . See http://www.cplusplus.com/reference/string/ but remember that is for C++ not for C.

[Kaustubha Govind]

Also, you need to have your Convert function in a separate file, and simply call it in the Outputs pane using something like:

out1 = Convert(in1);

Note: the names 'in1' and 'out1' might change depending on how you've named your ports in the Data Properties pane.

[Zoltan]

Let me get this straight. I make a file which contains the function and it will have .c extension. Right? After this, i put the name of the file in the Libraries pane as a source file?

[Walter Roberson]

If you use a .c extension then that would be for C language code, which does not define "string" as a datatype.

[Kaustubha Govind]

Zoltan: Yes, that is correct.