title: cant convert lowercase to uppercase a string by preprocessor directive
body: <p>i made a program which converts lower case to upper case a string.i know how to convert a char to upper case via preprocessor directives but i dont know how to do it for a string.</p>
  
  <pre><code>#include&lt;stdio.h&gt;
  #include&lt;conio.h&gt;
  #include&lt;ctype.h&gt;
  #define UPPER([])  ([]-32)
  void fstring_convert(char string[]);
  void main(void)
  {
  char string[40];
  printf("Enter a string:");
  gets(string);
  fstring_convert(string);
  printf("%s",string);
  getch();
  }
  
  void fstring_convert(char string[])
  {
      int i;
   for(i=0; ;i++)
   {
      if(string[i]==' ')
      {
          string[i]=string[i+1];
      }
      if(isdigit(string[i]))
      {
      string[i]+=1;
      }
      UPPER('string[i]');
      if(string[i]=='\0')
      break;
   }
  
  }
  </code></pre>