Adding a Function Prototype

Begin by adding a function prototype to the function declaration list:

static void max CC_ARGS((int, double * >= maxlen) break; /* don't exceed maxlen */
    if (isalnum(*ptr)) {
       if (flag) *p = islower(*ptr)?toupper(*ptr):*ptr;
       else *p = isupper(*ptr)?tolower(*ptr):*ptr;
       flag = 0;
    } else {
       flag = 1;
       *p = *ptr;
    }
     p++; ptr++;
  }
  *p = '\0';
  return;
}

Note the use of the CC_ARGL, CC_ARG, and CC_LARG macros. You can also write the code as follows (only the first five lines are shown):

static void initcap(argc,argv,result,maxlen)
int argc;       /* Number of actual arguments */
char* argv[];   /* Pointers to arguments: */
char* result;   /* Where to store result */
int maxlen;     /* Result's maximum length */