 The magazine of the Melbourne PC User Group Xbase Programming - Part 2 Gary Taig garyt@melbpc.org.au |
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Last month I made too many of those "we'll cover that next month" promises as this month has been one of the busiest for a long time. However, the code below will enable you to enter data into your Sample Membership
Database. Read this, then key it in and test it out. [Download program in text format.]
My unexpected lateness means we have a fixed amount of space because the magazine is just about to go to bed. This sample program code is bare minimum code only. It has no frills and no specials but naturally that will make it easier to follow. Lets take it from the top.
After the PROGRAM HEADER we set up our environment so that the screen appears exactly as we want it Each setting has a special purpose but we cant cover them all now. The first one we MUST look at is SET PROCEDURE TO mbinput. This tells our Xbase System that the program contains PROCEDURES - known in some circles as SUBROUTINES. If you give your program a name other than MBINPUT.PRG you must change the name in that statement to suit. The .PRG is not required in SET PROCEDURE TO because Xbase knows you are gluing it a PROGRAM NAME.
The next line. DO MAIN, tells Xbase to go off and DO the procedure named MAIN. Later, when it returns from MAIN, it sets the color back to normal, closes the file and dumps you at the DOT PROMPT. If you wish to end your Xbase session at that point, simply replace that particular RETURN with QUIT.
The PROCEDURE named MAIN is our main program for the moment and processing will continue in MAIN until we decide to finish our data entry session. I had to delete some lines due to space but you can easily key them in, it's all good practice.
The first thing we do in MAIN is check for the existence of our data file named MEMBERS.DBF and its associated .DBT Me. You must replace the three lines that check for the .DBT Me. Just type them exactly as I did for MEMBERS.DBF, replacing "MEMBERS.DBF" with "MEMBERS.DBT". Also, make the screen message location ® 11.10 instead of repeating the @ 10,10 because if both files happen to be missing Xbase will paint the first message on screen row 10, then immediately overwrite it with the next message on row 10. You will not see the first message.
Notice we have created a special memory variable named "goback". That is a LOGICAL variable, set initially to false (.F.), and it will be set to true (.T.) ONLY IF one of those files is missing. Our next statement then is to check the value of "goback". The program line that says "IF GOBACK", with nothing following, actually means "If the value of the variable named GOBACK is TRUE"... then perform the following. If it's found to be NOT true, (false), program flow will continue on after the ENDIF.
Our sample system has four indexes. Only one of them remains now so you have to key in the other three just like we did above. They are as follows:
|
surnamdx.ndx INDEX ON surname fullname.ndx INDEX ON sumame+first+init2 pcode.ndx INDEX ON post_zip |
Carefully repeat the same bit of code and replace where appropriate with the names I have even you. This really is fun, isn't id All good practice.
Next we create an EMPTY date variable. That allows the operator to key in any date. More on this in another lesson. We also create a variable named SPCE10 at this point and we store ten blank spaces in it. See if you can identify where we use it and what it does?
Next we create more variables by declaring them PUBLIC. It's necessary to create them here in MAIN because we cannot do that in a PROCEDURE or some other program that might subsequently be called by MAIN.]
When MAIN calls another program and there just happens to be some variables created within that other program, the variables are released and the used memory is freed up again at the time of return. The variables and contents are lost.
We avoid that problem by creating the variables now. Called programs can now use them, and modify them, but they cannot release them.
Immediately after the PUBLIC declaration we have a line that says DO BLNKVARS. This tells Xbase to run off and find a PROCEDURE (or a separate PROGRAM) named BLNKVARS and execute it. It will do just that if it can find one, then it will return to here and continue processing.
If we had left out the "SET PROCEDURE TO mbinput" back at the start, Xbase would crash at this point because it would not find BLNKVARS. It would not know to look further down inside this program that it's currently executing.
When called, the procedure named BLNKVARS actually stores lots of BLANK SPACES to the
variables we made PUBLIC earlier.
Back to our MAIN program. We set the color for our field titles and then start processing at the top
of this page, painting words on the screen at ROW, COLUMN locations. When we say @ 1,20 we mean
at ROW ONE, COLUMN 20.
After our titles we draw some boxes, and then we place the variables full of blank spaces, on screen,
for the operator to enter some data.
Each of the variables we created and filled with varying numbers of blank spaces is placed on the
screen for data entry by use of the GET and READ.
As you issue each of those GETs the appropriate variable is painted at the designated ROW,
COLUMN position. Then, when the READ command is encountered by the program it places
the cursor at each of these in turn and accepts operator input.
Processing STOPS at the READ command while you enter all your DATA into the blank variables.
When you have completed this and you press one of the suggested key combinations to conclude the
READ the program checks to see what you pressed and branches accordingly.
Notice if you press the Ctrl-PgUp key, this has a
readkey( ) value of 290, the program runs off and does the PROCEDURE named
PUTITIN. There we add a new blank record to the file, store all the data just obtained from the operator and return.
Immediately upon return the program again runs BLNKVARS to store more blank spaces in the
variables, ready for the next GET and READ.
Unfortunately I am out of space. Play with this and practice as many variations as you can until
next month where I promise, we will cover this again, in much greater detail.
Enjoy!
[ Continued in December Part 3 article.]
| ************************************************** * Program I MBINPUT.PRG * Author I {your name) * Date {date) * purpose Membership Data entry. * Part 2 - Melb PC Xbase Programming Tutorial. * 1. set up environment SET talk off SET bell off SET safety OFF SET date british SET status OFF CLEAR SET PROCEDURE TO MBINPUT DO main SET color TO SET status ON close databases RETURN PROCEDURE MAIN ************** goback = .F. * 1. Check the main file hasn't been deleted if .NOT. file("members.dbf") @ 10, 10 SAY "Main datafile is MISSING!" goback = .T. endif ** repeat this for MEMBERS.DBT (see text) if goback clear typeahead wait space (9)+"Please recreate MEMBERS.DBF"' RETURN endif * 2. Open file and create required indexes. SELECT 1 USE members ** check index files recreate if missing if .NOT. file("memberdx.ndx") INDEX ON member TO memberdx endif ** repeat for surnamdx.ndx fullname.ndx pcode.ndx * make empty date variable for convenience blnkdate = CTOD(' / / ') spce10 = space(10) && column width (see text) PUBLIC m_init2,m_init3,m_floor,m_state,m bldg name PUBLIC m_title,m_unit_flat,m_str_no,m_fee PUBLIC m_phcode_ah,m_phcode_bh,m_member,m_assist PUBLIC m_phone ari,m_phone bh,m_fax_ah,m_fax bh, PUBLIC m_str_type,m_post_zip,m_mail_area,m_married PUBLIC m_first,m_pref_name,m_country,m_surname PUBLIC m_street,m_city sub,m_donation PUBLIC m_d_birth,m_joined,m_valid_to DO BLNKVARS * blank variables created - now paint input screen SET COLOR TO rg/n @ 1, 20 SAY "(club name) Membership Data Entry" @ 3, 2 SAY "Member Number:" @ 3, 29 SAY "Name:" @ 3, 49 SAY "Surname:" @ 4, 2 SAY "Preferred name:" @ 4, 33 SAY "Initials:" @ 4, 49 SAY "Title:" @ 7, 2 SAY "Unit/Flat:" @ 7, 19 SAY "Floor/Level:" @ 7, 36 SAY "Building Name:" @ 8, 2 SAY "Street No:" @ 8, 19 SAY "Street Name:" @ 8, 54 SAY "Street Type:" @ 9, 2 SAY "City:" @ 9, 36 SAY "State:" @ 10, 2 SAY "Post Code:" @ 10, 26 SAY "Mail Area:" @ 10, 53 SAY "Country:" @ 13, 5 SAY "Contact Business: Area Code:" @ 13, 47 SAY "Phone:" @ 13, 64 SAY "Fax:" @ 14, 1 SAY "Information After Hours:" @ 17, 2 SAY "Date/Birth:" @ 17, 27 SAY "Date Joined:" @ 17, 50 SAY "Membership Valid to" @ 18, 2 SAY "Married Y/N:" @ 18, 27 SAY "Membership Fee:" @ 18, 57 SAY "Donations ?" @ 19, 2 SAY "Duty:" @ 19, 37 SAY "Name Assistant:" @ 21, 2 SAY "Main Interest:" @ 21, 27 SAY "Comments:" @ 21, 47 SAY "Notes:" @ 23, 2 SAY "Ctrl-PgDn Save EXIT I (esc); discard entry I Ctrl-PgUp - Save ADD MORE" SET COLOR TO g/n @ 2, 0 to 5, 79 @ 6, 0 to 11, 79 @ 12, 15 to 15, 79 @ 16, 0 to 22, 79 SET COLOR TO w+/b addmore = .T. do while addmore @ 3, 18 GET M_MEMBER picture "@!" @ 3, 35 GET M_FIRST @ 3, 58 GET M_SURNAME picture "@!" @ 4, 18 GET M_PREF_NAME @ 4, 43 GET M_INIT2 picture "@!" @ 4, 46 GET M_INIT3 picture "@!" @ 4, 58 GET M_TITLE @ 7, 13 GET M_UNIT_FLAT @ 7, 32 GET M_FLOOR @ 7, 52 GET M_BLDG_NAME @ 8, 13 GET M_STR_NO @ 8, 32 GET M_STREET @ 8, 67 GET M_STR_TYPE @ 9 13 GET M_CITY_SUB picture "@!" @ 9, 45 GET M_STATE picture "@!" @ 10, 13 GET M_POST_ZIP picture "9999" @ 10, 38 GET M_MAIL_AREA @ 10, 62 GET M_COUNTRY @ 13, 40 GET M_PHCODE_AH @ 13, 54 GET M_PHONE_BH @ 13, 70 GET M_FAX_BH @ 14, 40 GET M_PHCODE_BH @ 14, 54 GET M_PHONE_AH @ 14, 70 GET M_FAX_AH @ 17, 16 GET M_D_BIRTH @ 17, 40 GET M_JOINED @ 17, 70 GET M_VALID_TO @ 18, 16 GET M_MARRIED picture "Y" @ 18, 44 GET M_FEE picture "999999.99" @ 18, 70 GET M_DONATION picture "Y" @ 19, 16 GET M_DUTY @ 19, 53 GET M_ASSIST READ DO CASE case readkey() = 12 .OR. readkey() = 268 RETURN case readkey () = 14 .OR. readkey () = 270 RETURN case readkey() = 290 DO PUTITIN DO BLNKVARS case readkey() = 34 LOOP case readkey() = 291 DO PUTITIN addmore = .F. case readkey() = 35 addmore = .F. OTHERWISE loop ENDCASE ENDDO RETURN PROCEDURE PUTITIN APPEND BLANK REPLACE MEMBERS->MEMBER WITH m_member REPLACE MEMBERS->FIRST WITH m_first REPLACE MEMBERS->SURNAME WITH m_surname REPLACE MEMBERS->PREF NAME WITH m_pref_name REPLACE MEMBERS->INIT2 WITH m_init2 REPLACE MEMBERS->INIT3 WITH m_init3 REPLACE MEMBERS->TITLE WITH m_title REPLACE MEMBERS->UNIT FLAT WITH m_unit_flat REPLACE MEMBERS->FLOOR WITH m_floor REPLACE MEMBERS->BLDG NAME WITH m_bldg _ame REPLACE MEMBERS->STR NO WITH m_str_no REPLACE MEMBERS->STREET WITH m_street REPLACE MEMBERS->STR TYPE WITH m_str_type REPLACE MEMBERS->CITY SUB WITH m_city_sub REPLACE MEMBERS->STAT WITH m_state REPLACE MEMBERS->POST ZIP WITH m_post_zip REPLACE MEMBERS->MAIL AREA WITH m_mail_area REPLACE MEMBERS->COUNTRY WITH m_country REPLACE MEMBERS->PHCODE AH WITH m_phcode_ah REPLACE MEMBERS->PHONE BH WITH m_phone_bh REPLACE MEMBERS->FAX BH WITH m_fax_bh REPLACE MEMBERS->PHCODE BH WITH m_phcode_bh REPLACE MEMBERS->PHONE AH WITH m_phone_ah REPLACE MEMBERS->FAX AH WITH m_fax_ah REPLACE MEMBERS->D-BIRTH WITH m_d_birth REPLACE MEMBERS->JOINED WITH m_joined REPLACE MEMBERS->VALID TO WITH m_valid_to REPLACE MEMBERS->MARRIED WITH m_married REPLACE MEMBERS->FEE WITH m_fee REPLACE MEMBERS->DONATION WITH m_donation REPLACE MEMBERS->DUTY WITH m_duty REPLACE MEMBERS->ASSIST WITH m_assist RETURN PROCEDURE BLNKVARS STORE space(1) TO m_init2,m_init3 STORE space(2) TO m_floor STORE space(3) TO m_state STORE space(4) TO m_title,m_unit_flat STORE space(4) TO m_phcode ah,m_phcode bh STORE space(5) TO m_str_no STORE space(7) TO m_phone_ah,m-phone bh STORE space(7) TO m_fax_ah,m_fax bh STORE space(8) TO m_member STORE spce10 TO m_str_type,m_post_zip STORE spce10 TO m_mail_area STORE space(12) TO m_first,m_pref name STORE space(15) TO m_country STORE space(20) TO m_surname,m_street STORE space(20) TO m_city sub,m_duty STORE space(25) TO m_bldg name,m_assist STORE .F. to m_married,m_donation STORE blnkdate to m_d_birth,m_joined STORE blnkdate to m_valid_to STORE 0 to m_fee RETURN |
Reprinted from the November 1991 issue of PC Update, the magazine of Melbourne PC User Group, Australia
