introduction to basic programming ken r. hall, ph.d. ken r. hall consultants portland, oregon
TRANSCRIPT
Introduction toBASIC Programming
Ken R. Hall, Ph.D.
Ken R. Hall Consultants
Portland, Oregon
Speaker’s Qualifications
• Ken Hall is a PICK/SHIMS consultant and owner of Ken R. Hall Consultants.
• Ken has over 25 years experience developing applications in PICK, Universe, and Unidata.
• Ken is a reseller of IBM U2 (Universe) and Raining Data database products.
• Ken has developed business applications for distributors, retailers, mail order houses, manufacturers, and leasing companies.
Learning Objectives
• As a result of this presentation, you will be able to:– Look at a BASIC program with an editor – Read the statements in a BASIC program– Know where to look for more information
when you don’t understand the program
Presentation Agenda
• Concepts and Terminology• Creating and Viewing
Programs• An Introduction to commonly
used BASIC statements• Where to find more
information about BASIC
UniVerse Database Concepts
• Multivalue database structure– Accounts and Files– Keys or Item-Ids– Variable length Record Structure
• Each subdivision has a separator character
– Records or Items• Fields or Attributes
– Values within Fields» Subvalues within Values
Terminology of PICK/BASIC
• Statements – a line of BASIC codeCUST.NO = CUSTOMER.REC<1>
• Constants and Literals – things that don’t changeOK.RESPONSE = “YES”
• Assignment Statements – changing valuesNUMBER.PRODS = 0
• Functions – things available from the systemTODAY = DATE()
• Operators – symbols that associate variables– Arithmetic, Logical, or String
+, -, *, /; #, =, GE, LE, LT, GT; :
Creating and Viewing Programs
• Create a File to store programs– CREATE.FILE YOURBP
• Naming a program• Use the Editor, ED or WED, to create/edit a program
– ED YOURBP YOUR.PROGRAM
• Compile the program with BASIC command– BASIC YOURBP YOUR.PROGRAM
• Activate the program with RUN command– RUN YOURBP YOUR.PROGRAM
• Activate the program with CATALOG command– CATALOG YOURBP YOUR.PROGRAM
Fundamental BASIC Statements
• PROMPT• PRINT• CRT or DISPLAY• INPUT• END• STOP• IF … THEN … ELSE• LEN(), ABS(), DATE(),TIME• OPEN• READ• WRITE• GO or GOTO
• * comments for clarity
• * looping• FOR
• NEXT
• LOOP
• UNTIL or WHILE• REPEAT
• * finding records
• SELECT
• READNEXT
Adding Comments for Clarity
• Comment lines start with *, !, or REM– * PROGRAM TO PRINT INVOICES FOR XYZ COMPANY– ! This line is also a comment
• Programs often start with comments that explain the purpose of the program and the author
• Comment lines can be used as spacers for clarity– *– * TODAY is a constant to store the current date– TODAY = DATE()– *
• Comments document modifications to the program
Simple Input of Information
• PROMPT defines the character displayed when user input is requested by the program– * send the colon when input is requested– PROMPT ‘:’
• INPUT requests user input from the keyboard– Puts prompt character at current cursor position– Input is completed by hitting Enter key – INPUT CUSTOMER.NAME
• Input can be positioned and/or formatted– INPUT @(ROW,COL):CUSTOMER.NAME
Output of Data
• PRINT sends data to either screen or printer– Controlled with PRINTER ON or PRINTER OFF
statements– PRINT “This is a test of output”– PRINT CUSTOMER.NAME
• CRT sends data to the screen– CRT YOUR.NAME
• Output can be positioned and/or formatted– PRINT @(ROW,COL):CUSTOMER.NAME “L#25”
Marking the END
• The END statement is used to:– Marks the end of the program
* the last line is belowEND
– Marks the end of a multi-line statementIF DAYS.PAST.DUE > “90” THEN PRINT “OVER 90 DAYS PAST DUE”END
• The STOP statement causes the program to terminate. * the next line exits this program after Q is typed IF DATA.INPUT = ‘Q’ THEN STOP END
Logical Control with IF … THEN
• Single line statement:IF X > “10” THEN PRINT “More than ten” ELSE PRINT “Ten or less”
• Multi-line IF statement:IF X > “10” THEN
PRINT “X is greater than ten”
END ELSE
PRINT “X is ten or less”
END
Logical Control with LOOP
• Single line LOOP statement: X = 0 LOOP X = X + 5 WHILE X < 100 DO PRINT “X is ”: X REPEAT * Go here when X is equal to or greater than 100
• Multi-line LOOP statement: X = 0
LOOP X = X + 5 WHILE X < 100 DO
PRINT “X is ”:X REPEAT
* Go here when X is equal to or greater than 100
OPEN file and READ data
• Use OPEN to gain acces to a fileOPEN ‘CUSTOMER’ TO CUST.FILE ELSE STOP
• Use READ to read a record from a fileCUST.NO = ‘1023’
READ CUSTOMER.REC CUST.FILE, CUST.NO THEN
CRT CUSTOMER.REC<1> ; * display customer name
END ELSE CRT ‘CUSTOMER ‘:CUST.NO:’ not found’
WRITE data to a file
• Use WRITE to save data to a recordWRITE CUSTOMER.REC ON CUST.FILE, CUST.NO
• Use WRITEV to save a variable in a field CUST.NO = ‘1023’
CUSTOMER.NAME = “ABC ELECTRIC CO.”
WRITEV CUSTOMER.NAME ON CUST.FILE, CUST.NO, 1
• Corresponding READV reads a field READV CUSTOMER.NAME FROM CUST.FILE, CUST.NO, 1 ELSE
CUSTOMER.NAME = ‘UNKNOWN’ END
Sample BASIC Program
* A simple program that opens a file and reads data PROMPT ''10: CRT 'Enter first file name: ': INPUT F1 IF F1 = '' OR F1 = 'X' OR F1 = "." THEN STOP OPEN F1 TO FILE1 ELSE CRT 'CANNOT open file ':F1 GO 10 END READ TEST.REC FROM FILE1, ‘TEST’ THEN CRT ‘TEST.REC IS ‘:TEST.REC END ELSE CRT ‘TEST IS NOT ON FILE’ END STOP END
PICK BASIC Book
• Jonathan E. Sisk'sPick/BASIC: A Programmer's Guide
Found on the web at: http://www.jes.com/pb/index.html
IBM UniVerse Documentation
• To view or get copy of UniVerse BASIC manual, follow the link below:
Found on the web at: http://www-306.ibm.com/software/data/u2/pubs/library/
Click on UniVerse version that you want.Choose “install doc set” to download the entire UV documentation set with installer.
Q&A
