Q59727: Legal Data Delimiters When Using INPUT #n Statement

Article: Q59727
Product(s): See article
Version(s): 2.00 2.01 3.00 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | SR# S900312-105 B_BasicCom docerr | mspl13_basic
Last Modified: 10-AUG-1990

This article corrects several documentation errors concerning how to
delimit data in a sequential file that is to be read by the INPUT#
statement.

The INPUT# statement reads data items from a sequential device or file
and assigns them to variables. If the data items in the file are
numeric values, they should be separated with a space, carriage return
(CR), or comma. Strings should be separated with a carriage return or
a comma, or enclosed in double quotation marks. A linefeed (LF) by
itself should not be used as a file delimiter in either case.

The following references incorrectly state that a linefeed may be used
as a delimiter between data items in a file. These references also
omit the fact that string data may be delimited by a comma.

1. Page 304 of the "Microsoft QuickBASIC Compiler" manual for versions
   2.00, 2.01, and 3.00

2. Page 225 of the "Microsoft QuickBASIC 4.0: BASIC Language
   Reference" manual for QuickBASIC versions 4.00 and 4.00b

3. Page 225 of the "Microsoft BASIC Compiler 6.0: BASIC Language
   Reference" manual for versions 6.00 and 6.00b

4. Page 167 of the "Microsoft BASIC 7.0: Language Reference" manual
   for Microsoft BASIC Professional Development System (PDS)
   versions 7.00 and 7.10

5. Under the INPUT# statement in the QB Advisor online Help system
   for QuickBASIC version 4.50

In addition, all the above references (except #4) incorrectly state
that string data items may be delimited with spaces. Only numeric data
items may be delimited with spaces. String data items must be
delimited by a comma or a carriage return, or enclosed in double
quotation marks.

If you need some other character, such as a linefeed by itself, to act
as a delimiter, then a file may be read in BINARY mode. When a file is
opened in BINARY mode, the data is not interpreted and the program
must be written to interpret or "filter" each character as needed.

The following is a description of how the INPUT# statement handles a
linefeed, carriage return, space, and comma if one of these characters
is used as a delimiter between data items. Also, the program below
exhibits the behavior of these characters when used as delimiters.

Numeric Input Syntax: INPUT #n, <numeric variable>
--------------------------------------------------

This reads a linefeed in as a numeric value instead of a delimiter.
Each time a linefeed is encountered, the linefeed character is treated
as a data item and a value of 0 is returned for the input.

A carriage return, space, or comma functions correctly as a delimiter
for numeric input.

String Input Syntax:  INPUT #n, <string variable>
-------------------------------------------------

This ignores the linefeed character completely. If two data items are
separated by a linefeed and read in as strings, the two data items are
read in as one string that is a concatenation of the two data items.

A space between two data items causes the two data items to be read in
as one string, and the space is an actual character in that string.

A carriage return or comma functions correctly as a delimiter. If a
comma appears between a pair of double quotation marks, the comma is
treated as part of the string. A carriage return always acts as a
delimiter, terminating any string delimited by a beginning double
quotation mark.

Sample Code
-----------

CLS
INPUT "Enter 'q' to quit.  Enter 'c' to continue==> ", start$

WHILE start$ <> "q"
 CLS

 OPEN "numeric.dat" FOR OUTPUT AS #1
 OPEN "string.dat" FOR OUTPUT AS #2

 PRINT "Input the ASCII code for the delimiter you wish to attempt:"
 PRINT "   10 = line feed"
 PRINT "   13 = carriage return"
 PRINT "   32 = space"
 INPUT "   44 = comma =============>", delimit%

 num1% = 5: num2% = 10        'define data to be put in numeric file
 str1$ = "hi": str2$ = "mom"  'define data to be put in string file

 PRINT #1, num1%; CHR$(delimit%); num2%  'write data separated by
 PRINT #2, str1$; CHR$(delimit%); str2$  'chosen delimiter to file

 CLOSE

 OPEN "numeric.dat" FOR INPUT AS #1
 OPEN "string.dat" FOR INPUT AS #2

 PRINT
 count% = 0
 PRINT "This file contains the numeric values 5 and 10."
 PRINT "==============================================="
 DO UNTIL EOF(1)
     count% = count% + 1
     INPUT #1, inp1%
     PRINT "Value read in after"; count%; "input(s):"; inp1%
 LOOP

 PRINT
 count% = 0
 PRINT "This file contains the string values 'hi' and 'mom'."
 PRINT "===================================================="
 DO UNTIL EOF(2)
     count% = count% + 1
     INPUT #2, inp2$
     PRINT "Value read in after"; count%; "input(s): "; inp2$
 LOOP

 CLOSE

 PRINT : PRINT
 INPUT "Press 'q' to quit.  Press 'c' to continue==> ", start$
WEND
END