Using MC++ How do you pass a String between forms?

I have been trying to pass a string from form2 to form1. form1 then displays the string.
I have a button on form1 that creats an instance of form2. form2 asks for the user input and sends it back to form1. However i am not sure how to pass from form2 back to form1. Tried using public variables but that did not work. Any suggestions or online tutorials would help. Thanks

Code:

void form1(void){
  char achIn[100];
  form2(achIn);
}

char *form2(char *inStr){
  strcpy(inStr, "input");
  return(inStr);
}