Chapter 14 - Revision history

John: fix bad example

2018-04-11T19:43:44Z

fix bad example

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	Besides the line number and the OPEN keyword, the syntax of the OPEN statement contains five major parts: the file number, the file identification string, the file type, and the type of use and the method of access. Keep in mind that, while the name and type of a file must remain constant, the same internal file can be opened for all different types of uses and methods of access. The following OPEN statement creates the file CHEKBOOK.INT:		Besides the line number and the OPEN keyword, the syntax of the OPEN statement contains five major parts: the file number, the file identification string, the file type, and the type of use and the method of access. Keep in mind that, while the name and type of a file must remain constant, the same internal file can be opened for all different types of uses and methods of access. The following OPEN statement creates the file CHEKBOOK.INT:

	500 open #5: Name="Checkbook.int, recl=63,new", internal, output, sequential		500 open #5: "Name=Checkbook.int, recl=63,new", internal, output, sequential

	The parts are: line number, OPEN, file number, file ID string, file type, method of access.		The parts are: line number, OPEN, file number, file ID string, file type, method of access.

Laura: /* The SEQUENTIAL method of access with INTERNAL files */

2017-03-20T17:37:14Z

The SEQUENTIAL method of access with INTERNAL files

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	Each of the seven fields (check number, amount, deposit/withdrawal flag, etc.) is described in the first column in the layout sheet. The second column describes format of the fields; if you think back to the chapter that discussed formatted printing and use of the FORM statement, you should recognize the meanings of the figures in this column. The third column lists the record positions that the fields will occupy. Notice that there are no extra spaces between fields; since internal files cannot be seen by people anyway, there is no reason to make them readable by adding spaces between fields.		Each of the seven fields (check number, amount, deposit/withdrawal flag, etc.) is described in the first column in the layout sheet. The second column describes format of the fields; if you think back to the chapter that discussed formatted printing and use of the FORM statement, you should recognize the meanings of the figures in this column. The third column lists the record positions that the fields will occupy. Notice that there are no extra spaces between fields; since internal files cannot be seen by people anyway, there is no reason to make them readable by adding spaces between fields.

	To take the first field in the above layout as an example, the information that you should be able to determine from this entry is that check number is a numeric field which is 5 digits long and located in the ~~fist~~ 5 bytes of the record.		To take the first field in the above layout as an example, the information that you should be able to determine from this entry is that check number is a numeric field which is 5 digits long and located in the first 5 bytes of the record.

	You might note that the third field is only one byte long. Can anything important be stored in a one-byte field? You betcha! This little guy contains a D if the record is a deposit and a W if it is a withdrawal. This one-byte indicator, sometimes called a flag, is stored in position 16. In future references to the CHEKBOOK.INT file, we will assume that when there is a W in position 16 but no check number, the transaction that occurred involved a withdrawal that was not a check (perhaps it was a bank service charge or a cash machine withdrawal).		You might note that the third field is only one byte long. Can anything important be stored in a one-byte field? You betcha! This little guy contains a D if the record is a deposit and a W if it is a withdrawal. This one-byte indicator, sometimes called a flag, is stored in position 16. In future references to the CHEKBOOK.INT file, we will assume that when there is a W in position 16 but no check number, the transaction that occurred involved a withdrawal that was not a check (perhaps it was a bank service charge or a cash machine withdrawal).

Laura: /* Using the REWRITE statement to change information in a file */

2017-03-17T18:59:39Z

Using the REWRITE statement to change information in a file

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	05910 PRINT “Are these totals correct?”		05910 PRINT “Are these totals correct?”
	05920 LINPUT YESNO$		05920 LINPUT YESNO$
	05930 YESNO$=LTRM$(YESNO$(1:1)		05930 YESNO$=LTRM$(YESNO$(1:1))
	05940 IF YESNO$=”Y” OR YESNO$=”y” THEN STOP		05940 IF YESNO$=”Y” OR YESNO$=”y” THEN STOP
	05950 EXECUTE “FREE CHEKBOOK.INT”		05950 EXECUTE “FREE CHEKBOOK.INT”

Laura: /* Quick Quiz 14.9 */

2013-08-16T17:20:54Z

Quick Quiz 14.9

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	NEXT:[[Chapter 15]]		NEXT:[[Chapter 15\|The RELATIVE method of access for INTERNAL files]]

	[[BR Tutorial\|Back to Index]]		[[BR Tutorial\|Back to Index]]

Laura at 01:18, 16 July 2013

2013-07-16T01:18:46Z

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	<noinclude>		<noinclude>
	[[Category:Tutorial]]		[[Category:Tutorial 1]]
	</noinclude>		</noinclude>

Laura: /* Quick Quiz 14.9 */

2013-07-15T21:05:21Z

Quick Quiz 14.9

← Older revision		Revision as of 21:05, 15 July 2013
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	[[BR Tutorial\|Back to Index]]		[[BR Tutorial\|Back to Index]]

			<noinclude>
			[[Category:Tutorial]]
			</noinclude>

Laura: /* Quick Quiz 14.9 */

2013-07-03T22:44:29Z

Quick Quiz 14.9

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	2. To be able to read sequentially from an internal file, the best way to code the OPEN statement is:<br>		2. To be able to read sequentially from an internal file, the best way to code the OPEN statement is:<br>

	a) DISPLAY, OUTIN, SEQUENTIAL<br>		a) DISPLAY, OUTIN, SEQUENTIAL<br>
	b) INTERNAL, OUTPUT, RELATIVE<br>		b) INTERNAL, OUTPUT, RELATIVE<br>
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	3. True or False: The best way to add records to the end of a long data file for OUTPUT,SEQUENTIAL, then use the RESTORE statement.		3. True or False: The best way to add records to the end of a long data file for OUTPUT,SEQUENTIAL, then use the RESTORE statement.

	Answers~~<br>~~		[[Answers 14.9]]<br>
	~~1. a~~. ~~Begining of the file~~<br>
	~~b. End of the file<br>~~
	~~c. Begining of the file<br>~~
	~~d. Begining of the file<br>~~
	~~2. c<br>~~
	~~3. True<br>~~

	NEXT:[[Chapter 15]]		NEXT:[[Chapter 15]]

	[[BR Tutorial\|Back to Index]]		[[BR Tutorial\|Back to Index]]

Laura: /* Quick Quiz 14.8 */

2013-07-03T22:43:51Z

Quick Quiz 14.8

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	c) OUTIN.<br>		c) OUTIN.<br>

	~~Answer:<br>~~		[[Answers 14.8]]<br>
	1. ~~a<br>~~
	~~2. c~~<br>

	===14.9 The file pointer and the RESTORE statement===		===14.9 The file pointer and the RESTORE statement===

Laura: /* Quick Quiz 14.7 */

2013-07-03T22:43:24Z

Quick Quiz 14.7

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	====Quick Quiz 14.7====		====Quick Quiz 14.7====
	1. The purpose of the REWRITE statement is:<br>		1. The purpose of the REWRITE statement is:<br>

	a) To add new records to a file.<br>		a) To add new records to a file.<br>
	b) To change existing records in a file.<br>		b) To change existing records in a file.<br>
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	2. To use the REWRITE statement, a file must be opened with the keyword:<br>		2. To use the REWRITE statement, a file must be opened with the keyword:<br>

	a) INPUT.<br>		a) INPUT.<br>
	b) OUTPUT.<br>		b) OUTPUT.<br>
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	3. When a REWRITE statement updates one field in the record, fields in the record which are not specified in the associated FORM statement:<br>		3. When a REWRITE statement updates one field in the record, fields in the record which are not specified in the associated FORM statement:<br>

	a) Will be changed to blank spaces.<br>		a) Will be changed to blank spaces.<br>
	b) Will remain unchanged.<br>		b) Will remain unchanged.<br>
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	4. With files opened for sequential processing, the REWRITE statement can only make changes to:<br>		4. With files opened for sequential processing, the REWRITE statement can only make changes to:<br>

	a) The first record in the file.<br>		a) The first record in the file.<br>
	b) The last record read.<br>		b) The last record read.<br>
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	d) The next record pointed to by the file pointer.		d) The next record pointed to by the file pointer.

	~~Answer:<br>~~		[[Answers 14.7]]<br>
	1. ~~b<br>~~
	~~2. c<br>~~
	~~3. b<br>~~
	~~4. b~~<br>

	===14.8 More about OUTPUT, INPUT and OUTIN===		===14.8 More about OUTPUT, INPUT and OUTIN===

Laura: /* Quick Quiz 14.6 */

2013-07-03T22:42:31Z

Quick Quiz 14.6

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	5. After the Business Rules! system reads a record, the record stays in a memory buffer until when?<br>		5. After the Business Rules! system reads a record, the record stays in a memory buffer until when?<br>

	a) Until the next READ statement is executed.<br>		a) Until the next READ statement is executed.<br>
	b) Until the record is deleted.<br>		b) Until the record is deleted.<br>
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	6. Which Business Rules! function changes all string input to uppercase letters?<br>		6. Which Business Rules! function changes all string input to uppercase letters?<br>

	a) UPRC$<br>		a) UPRC$<br>
	b) UPCASE$<br>		b) UPCASE$<br>
	c) UPRCL$		c) UPRCL$

	~~Answer<br>~~		[[Answers 14.6]]<br>
	1. ~~True<br>~~
	~~2. True<br>~~
	~~3. False<br>~~
	~~4. True<br>~~
	~~5. a<br>~~
	6~~. a~~<br>

	===14.7 Deleting records===		===14.7 Deleting records===