convstrn.c

C function to convert strings.一个实用的C处理函数。

/* ******************************************************************
 * Function name : str_convert(string)
 *
 * Description  : This function is used to convert lower
 *                 case alpha character  to upper case and
 *                 upper case alpha characters to lower case.
 *
 * Variables      : string  -  This parameter is a character
 *                             pointer to the string that is to be
 *                             modified.
 *
 * Example       : strcpy(str,"ABC");
 *                 output = str_convert(str);    returns the string abc
 *                 strcpy(str,"abC");
 *                 output = str_convert(str);    returns the string ABc
 *
 * Rules         : 1) The function must be passed a character pointer
 *                    containing the address of the character string to
 *                    be converted.
 *
 *                 2) This function does not use a return value. Therefore
 *                    it may be defined using the "void" data type if
 *                    it is supported by your compiler.
 *
 *
 */
str_convert(string)
 char string[];
{ int count;
  count = 0;
  while ( string[count] != '\0' )
     { if ( string[count] >= 'A' && string[count] <= 'Z' )
	string[count] = string[count] + 'a' - 'A';
       else
	 if ( string[count] >= 'a' && string[count] <= 'z' )
	    string[count] = string[count] - 'a' + 'A';
       count++;
     }
}

/* ******************************************************************
 * Function name : str_count(string)
 *
 * Description   : This function counts the number of characters
 *                 contained within a specified character string.
 *
 * Variables      : string  -  This parameter is a character
 *                             pointer to the string that is to be
 *                             counted.
 *
 *
 * Example       : str_convert("abcd");       returns a 4
 *                 str_convert("ab");         returns a 2
 *
 * Rules         : 1) The function must be passed a character pointer
 *                    containing the address of the character string
 *                    being analyzed.
 *
 *                 2) The return value must be passed to an integer
 *                    variable.
 *
 *                 3) The string being analyzed must be followed
 *                    by a null terminator "\0" value.
 *
 *
 */
str_count(string,sub_string)
 char string[];
 char sub_string;
{ int count, index;
  count = index = 0;
  while ( string[count] != '\0' )
    {   if ( string[count++] == sub_string ) index++;
    }
  return(index);
}

/* ******************************************************************
 * Function name : str_lindex(string, sub )
 *
 *  Description   : This function returns an integer value, indicating
 *                  the first location of the specified sub-string
 *                  character within the string being analyzed.
 *
 * Variables      : string  -  This parameter is a character
 *                             pointer to the string that is to be
 *                             counted.
 *
 *                  sub     - This parameter contains the character
 *                            being searched.
 *
 * Example       : output = str_convert("abcde",'c');  returns a 3
 *                 output = str_convert("abcd",'d');   returns a 4
 *                 output = str_convert("abcd",'b');   returns a 2
 *
 * Rules         : 1) The function must be passed a character pointer
 *                    containing the address of the character string
 *                    being analyzed.
 *
 *                 2) The return value of this funtion must be passed
 *                    to an integer variable.
 *
 *                 3) The string being analyzed must be followed
 *                    by a null terminator "\0" value.
 *
 */
str_lindex(string,sub_string)
 char string[];
 char sub_string;
{ int index;
  index = 0;

  while ( string[index] != '\0' && string[index] != sub_string)
    ++index;

  return(index);
}

/* ******************************************************************
 * Function name : str_delete(string, start, no_char)
 *
 * Description   : Thi