PRODUCT  :  Borland C++                           NUMBER  :  1713
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  1/2

    TITLE  :  Detecting a Blank Line




  /*  BLANKLIN.C:

      Example of how to detect a blank line.
      This example uses the library function strpbrk which compares
      a string str1 against another string str2.  If any character
      in str2 exists in str1, strpbrk returns a pointer to the
      character in str2.  If there is no match strpbrk returns
      NULL.  The following example loads str2 with all non-Blank
      ASCII characters.  If strpbrk returns NULL, we know that
      there are only blank characters in str1.
      Note:
        In practical uses of this function, one might want to trim
        the size of the buffer nonBlank down to its minimum.  The
        code here uses a length of 255 for the purpose of clarity.
        255 will cover all ASCII codes, but nonBlank isn't going to
        contain all ASCII codes.  Therefore the practical
        programmer might want to examine nonBlank in the debugger
        to see exactly what minimum length is required and change
        the buffer size accordingly.
  */

  #include  <ctype.h>
  #include  <stdio.h>
  #include  <string.h>

  #ifdef  __cplusplus
  const int MaxLine   = 120;
  const int MaxASCII  = 255;

  #else
  # define  MaxLine   120
  # define  MaxASCII  255

  #endif

  int main (void)
  {
    FILE  *fp;
    char  buf [MaxLine];
    int   i;
    char  ni;
    char  *notABlankLine;
    char  nonBlank [MaxASCII];













  PRODUCT  :  Borland C++                           NUMBER  :  1713
  VERSION  :  All
       OS  :  All
     DATE  :  October 25, 1993                         PAGE  :  2/2

    TITLE  :  Detecting a Blank Line




    for (i = 1, ni = 0; i <= MaxASCII; i++)
    {
      /*  Fill up nonBlank with all non-blank ASCII characters.
          Note that i starts with 1 to avoid putting the NULL
          terminator at beginning of the string.
      */
      if  (!isspace (i))
      {
        nonBlank [ni++] = i;
      }
    }

    fp  = fopen ("BLANKLIN.CPP", "rt");
    if  (!fp)
      printf ("Open failed!\n");

    else
    {
      while (fgets (buf, MaxLine - 1, fp))
      {
        /*  Get lines until EOF is reached.
        */
        notABlankLine = strpbrk (buf, nonBlank);
        if  (notABlankLine)
          printf ("Line '%s' is not blank.\n", buf);

        else
          printf ("Line '%s' is a blank line.\n", buf);
      }
      printf ("End of File\n");

      fclose (fp);
    }
    return 0;
  }


  DISCLAIMER: You have the right to use this technical information
  subject to the terms of the No-Nonsense License Statement that
  you received with the Borland product to which this information
  pertains.