A Wikibookian believes this page should be split into smaller pages with a narrower subtopic. You can help by splitting this big page into smaller ones. Please make sure to follow the. Dividing books into smaller sections can provide more focus and allow each one to do one thing well, which benefits everyone. You can ask for help in dividing this book in the. Quite a lot of people were interested in this page (it was the most visited page in my former website) and so I feel that I must complete it. This page disappeared when GeoCities was closed (in fact it still contains some broken links to GeoCities pages), and it has been reloaded thank to some requests I got, for example on Facebook.
There you can find the 'Harbour MiniGUI' group, and others. When (and if) finished, it will prove a complete guide to Open Source Clipper programming. However, this page is still very incomplete. Recently (it is now ) I noticed a new Wikibook on a subject similar to this: I just threw in some stuff, for the moment. This page is derived from what I call the 'hubbub version'.
As a newbie to Wikibooks, I did not yet properly format the few sources in this page (Wikibooks has syntax highlighting for Clipper, but it is a bit buggy). If you check it, you will see misplaced links and so. This page definitely needs proofreading! A former version of this 'ebook':-) is at (I'd like to thank W. Birula for making me know it). I'd like to see this tutorial grow!
If someone on the newsgroup comp.lang.clipper or on the mailing lists HarbourUsers would give me help or clues. To apologize for its incompletedness, I can only say that this page contains everything I know about Clipper and xBase programming (in a given moment. I always try to learn new things.). I tried to adhere to the classical tutorials' bottom-up approach of showing all the basic function via very simple examples. The plan to include some bigger examples, with the top-down approach (how do I deal with this problem?) is suggested, but not yet pursued. I have decided to name this tutorial 'a Guide to Open Source Clipper(s)' and not 'a Guide to Open Source xBase' because I like the name Clipper, and as you can see by watching at the open source compilers I discuss (Clip and (x)Harbour) the influence of the name Clipper is great. Only X2c doesn't recall the name Clipper.
And now X# Modern xBase open source dialects are:. Harbour and xHarbour, which are the more active projects.
Clip, which is not being updated since 2013. X#, which will be a xBase for.NET X2c is too old - what use could be for a modern xBase the need to get its compiler from the Borland Museum? This Guide was born when I followed a small project (the port of an old Summer 87 application to Windows) and I saw the many Clipper compatible open source compilers available, but noticed also that there were no good tutorials and that the books about Clipper/xBase/Visual Objects and so on couldn't be found in any bookstore (not even in libraries!).
I think that the first part of the tutorial will cover the basic of the language, up to the procedural programming facilities. Part 2 will deal with the native DBF file support. Part 3 will explain OOP. Part 4 will cover other programming topics, and the last part will be about programming a user interface. This makes up for a nice introduction to computer science.
Thanks to bpd2000 for the nice link he provided. Michele Povigna. Part 1: The Common Ground. Chapter 1: Basic Language Tutorial. Chapter 2: Database Making. Part 2: Additions to the Language.
Chapter 3: Object Oriented Programming. Chapter 4: Some More Advanced Programming Topics. Part 3.
Function MAIN. This is an example clear? 'Hello, the weather is fine today' return (in GeoCities this and all other sources were highlighted by the on-line service CodeColorizer at ).
We will comment each line of the helloworld program. Function MAIN The first line defines a function named MAIN.
Defining such a function is not compulsory with Harbour, as if it is missed errors would occur during compilation, but I will keep it to make sure the examples work with all compilers. We will learn later how to define and use functions and procedures. This is an example The second line is a comment.
Commenting your programs will help you when you are to modify them later. If they aren't commenting, modifying them will be a very hard task.
It will be much more difficult if you are to modify programs written by others if they didn't comment them: figuring out what a program does using only its code is very difficult and even the most clean programming language may prove to be write-only if not properly commented. You can write comments in many different styles: using an asterisk (.), two sweeps (//), a double ampersand (&&) or a couple sweep-asterisk (/.) and asterisk-sweep (./), as you see below:. This is a comment. //.and so is this. /. This is an example of the fourth commenting style, which may span over several lines./ The second and the fourth commenting styles are derived from the C programming language, the first and the third are peculiar of the Clipper/xBase standard.
Clear No, the purpose of this command is not to make the source code clear (that would be too easy! It is up to us to write clear source code, and to do so we must comment it well), but instead to clean the screen.:-) You could also use clear screen or cls, although these two commands are not exactly the same of this clear (the difference will be clear later, when we can GET the point - then, you could also appreciate the pun in this paragraph - but will more likely not). What are commands?
Harbour commands are defined in the file std.ch via the #command macro directive. The first commands we encountered are defined by these lines: #command CLS = Scroll; SetPos(0,0) #command? = QOut( )?
'Hello, the weather is fine today' The? Is a command which means print. In the BASIC programming language, it is also an abbreviation for its print command (the syntax of xBase is quite similar to that of the BASIC programming language). In this case? Print the string Hello, the weather is fine today. Please note that the string return Return is used to terminate the function. We will explain later what the return exactly does.
Today Harbour needs not an explicitly defined main function/procedure. The following version of helloworld will compile and is exactly the same of the previous one. The Harbour Interpreter and Virtual Machine The program above, stored in a text file named hello.prg, can be run with the command hbrun hello.prg hbrun is an interpreter for Harbour.
This means that if we run it, we get to a screen with a 'Dot prompt' on its last line, where we can enter and run instructions. For example entering? 'Hello world' will get Hello world printed on the screen, but only after the interpreter hbrun itself is closed. To quit the interpreter and get the greeting printed type QUIT All in all, hbrun permits to feel how handling databases was done in the old dBase 'Dot prompt' mode - that is, like this: Running the compiler harbour (harbour.exe on Windows) on a printA.prg containing the line? 'A' will output a printA.c file. The bottom of this file reads.
&& example of compilation command && A: c: hb31 bin hbmk2 -quiet -oc: test.exe test.prg -run && please note that this example has not a MAIN function: I found that Harbour 3.0 can compile it anyway && an example of string concatenation? 'Hello' + ' ' + 'World!'
&& let us do now a few numerical computations, integer numbers are a good starting point? 3/2 SET DECIMALS TO 15 sqrt2= sqrt(2) && computing the square root of 2.? And printing it &&? Caporetto && if the line above was not commented, the compiler would issue the two following lines && Error BASE/1003 Variable does not exist: CAPORETTO && Called from TEST(8) && as xBase is not good at history, let us revise it: && we can then assign the correct date to this war caporetto:= ctod( ') a:= date && system date? A + 1 && will print tomorrow's date? A - caporetto && this will tell us how many days have passed since Caporetto's battle (difference between two dates) SET DECIMALS TO 2?
(a - caporetto) / 365?? ' years have passed since Caporetto's battle'? 1+1=3 && it will print '.F.' , that is, 'FALSE' (of course.) && The following two instructions should be discussed to expand on the subject of operator precedence? 1/2+2^3.(sqr(25)-3^2) From the following example (which runs) we see that Harbour is a weakly typed programming language: a variable, such as a in our example can be a number, and then become a string of text. && First we print the values of two expressions with the exponentiation operator?
3.3.3 && is 19683? 3.(3.3) && is 987 && Then we let our compiler tell us if they are the same? 3.3.3 = 3.(3.3) && result is.F.
&& We've a look at how our compiler deals with overflow and underflow.? 9.9.9 &&.? 1/9.9.9 && 0.00? -(9.9.9) &&. We see in this example that the exponentiation operator. is left-associative (where in mathematics exponentiation is a right-associative operation). The fact that 3.3.3 and 3.(3.3) give two different results means that parenthesis alter the operator precedence: whatever is enclosed in parenthesis is evaluated first.
Even when the operation is left-associative, the result of 9.9.9 is quite a 'large' number (91196809 to be precise, as you can easily check - maybe using some arbitrary precision calculator program, such as GNU bc, which is available on every Linux distribution and as a download for Windows at ) which exceeds the resources Harbour allocates for a number (which is called overflow) and it therefore prints 23 times a. to indicate this error. It also gives zero (0.00) if we try to compute its reciprocal (which is underflow). Overflow and underflow errors happen when the result of a computation is, respectively, too big or too small to be represented with the number of bits a compiler has allocated for the variable in which we're trying to store it in. Boolean Algebra & Flow Control We can print the result of a comparison, which is a Boolean value (represented as.T.
Or.F.), but they are useful with special words in order to branch or repeat the execution of one or more instructions. We have a Boolean expression when its result is true (whose xBase symbol is.T.) or false (.F.). The easiest way to get a Boolean result is to use a comparison (relational) operator: =, ,!=, #, , =, and. INPUT 'Key in a number: ' TO char char:= 'e' IF ( ( char = 'a'.OR.
Char = 'A' ).OR. ( char = 'e'.OR. Char = 'E' ).OR. ( char = 'i'.OR. Char = 'I' ).OR. Writing about writing book pdf. ( char = 'o'.OR.
Char = 'O' ).OR. ( char = 'u'.OR. Char = 'U' ) )? Char, ' is a vowel' ELSE? Char, ' is not a vowel' ENDIF This same thing could however be achieved better by the use of regular expressions. Looping DO WHILE, EXIT, LOOP, ENDDO are keywords used To repeatedly execute a series of statements (loop body) while a condition is true (i.e.
Its result is.T.). Loops come in several flavours: the pre-tested loop, the post-tested loop, and the definite iteration, which is done via a count-controlled loop (usually called a for loop). In practice, we may have a middle-tested loop as well, but no specific syntax for it. We need to put an EXIT statement within an already existing loop body to get this one. The next program we will key in is of some interest for the mathematicians (Real Programmers aren't afraid of maths, do you know this famous adage?) Here is it. && Function MAIN LOCAL number, sum, n && An anonymous contributor renamed the variable 'num' into 'number', increasing this short program readability, but the line above would give && Error E0030 Syntax error 'syntax error at 'LOCAL' Function MAIN LOCAL number, sum, n CLS? 'Let's sum up the first n odd numbers.'
INPUT 'How many numbers shall I sum up? ' TO n sum=0 number=1 DO WHILE number. 'I won't stop.' ENDDO This loop prints 'I won't stop.'
As long as 'true' is. It is thus called an infinite loop because the ending condition will never be satisfied. It is the first example of control flaw studied in computer science classes. By definition, you incur in an infinite loop every time you specify a tautology as the condition to be checked.
It is not always obvious to detect this and other control flaws and errors - it is indeed a process that involves the use of a specific piece of software called a debugger. Counter-controlled Loops The FOR.NEXT construct (counter-controlled loop) is useful when we know how many times we want the loop body be executed. We shall now use it to print out and revise multiplication tables.
CLEAR FOR I:= 1 TO 10 FOR J:= 1 TO 10 @i,j.4 SAY I.J PICTURE '999' NEXT NEXT this way we can print it much prettier. By the way, when nesting loops and branching statements, it becomes important (practitioning programmers say so, and in my little I agree) to arrange the indentations in order to make the program easier to read. In The Oasis are available 'source code beautifiers' such as dst314.zip. Harbour gives us the hbformat tool,.
PICTURE '999' is the instruction to specify we want the output format - as we specified three digits, the numbers in output will be printed as if they were three digits long, thus aligning them in our multiplication table. Functions and Procedures A function is a piece of code that returns a result every time it is called. Let us consider a function to convert Celsius into Fahrenheit. PROCEDURE Main // Random number between 0.01 and 0.99? HBRandom // Random number between 0.01 and 9.99? HBRandom(10) // Random number between 8.01 and 9.99? HBRandom(8,10) RETURN A good function would function as a 'black box', that is you can use it without worrying about how it internally works.
An example usually given at this point is that of driving a car: you can use it without worrying about how the engine works (do you know anybody which looked at the pistons of their new car before buying it?). Someone else designed the engine. But there may be problems: if we change our Celsius into Fahrenheit function as follows. FUNCTION cels2f( tempCelsius ) tempFahrenheit:= (tempCelsius.1.8 + 32) number:= number + 1 RETURN tempFahrenheit FUNCTION MAIN number:= 0? Cels2f( 100 )?
Number we'll get a side effect. This program output is 212.0 32.0 2 That is, our new function did not only return a value, it also increased by 1 the variable number. The Clipper Norton Guides read, 'A procedure in CA-Clipper is the same as a user-defined function, with the exception that it always returns NIL' , thus a procedure is really just a type of function that relies on these side effects to get something done. The utility of functions is that they improve program readability, maintainability. Splitting a program into functions is a good design approach, which lets breaking a complex problem into smaller, simpler problems ( top-down). Harbour has four different kinds of subroutines/subprograms:. the FUNCTION and.
the PROCEDURE (which is a FUNCTION with no return value),. the method (which has not an associated keyword, works like every object oriented programming language) and. the code block.
Why the Main Function? The main function is the designated start of a program written in C or C (Java uses a static main method). Since a procedure is a function that returns NIL, we can have a procedure main instead of a function main in our program.
With Harbour it is not necessary anymore. Another characteristic of variables: scope identifiers Variables have a name, a type, a scope and a lifetime which may be explicitly declared as (list below copied verbatim from ):.
LOCAL: Visible only within the routine which declared it. Value is lost upon exit of the routine. STATIC: Visible only within the routine which declared it. Value is preserved for subsequent invocations of the routine. If a STATIC variable is declared before any Procedure/Function/Method is defined, it has a MODULE scope, and is visible within any routine defined within that same source file, it will maintain its life for the duration of the application lifetime. PRIVATE: Visible within the routine which declared it, and all routines called by that routine. PUBLIC: Visible by all routines in the same application.
They do not make sense before we work with functions and procedures. /. Pc software free download. Work on the following. hbformat was run on this piece of code. need to provide comments, nest more functions and procedures to help figuring what goes on with scope modifiers./ STATIC x:= 9?
X PROCEDURE A LOCAL x:= 10? 'x from A=', x RETURN PROCEDURE B PRIVATE x:= 5?
'x from B=', x RETURN PROCEDURE C PUBLIC x:= -1? 'x from C=', x RETURN PROCEDURE D?
'x from D before updating value=', x x:= 12? 'x from D=', x RETURN PROCEDURE E?
'x from E=', x RETURN On running this, we get a strange output: 9 x from A= 10 9 x from B= 5 9 x from C= -1 9 x from D before updating value= -1 x from D= 12 9 x from E= 12 9 This program sets a variable x and five different procedures, A, B, C, D, E. The first three procedures define a variable x within themselves, assign it a value and print it. The fourth function assigns a new value to some variable named x without declaring it. The fifth function shows the value of some x variable, which happens to be the value of the fourth x variable. The main fact to remember here is that two variables are not the same, even if hey have the same name, provided they have different scopes and this feature is called shadowing. X PROCEDURE A LOCAL x:= 10? 'x from A=', x RETURN PROCEDURE B PRIVATE x:= 5?
'x from B=', x RETURN PROCEDURE C PUBLIC x:= -1? 'x from C=', x RETURN PROCEDURE D?
'x from D before updating value=', x x:= 12? 'x from D=', x RETURN PROCEDURE E?
'x from E=', x RETURN 9 x from A= 10 9 x from B= 5 9 x from C= -1 -1 x from D before updating value= -1 x from D= 12 12 x from E= 12 12 As static variables seem to require further informations (they work like C static variables), here is an example. // adapted from 'An example of static local variable in C' (from Wikipedia Staticvariable) FUNCTION func static x:= 0 /. x is initialized only once, the first time func is called./ x:= x+1? X RETURN FUNCTION main func // calls func a first time: it prints 1 func // value 1 was preserved; this time it prints 2 func // prints 3 func // prints 4 func // prints 5 See pascalvariablescope in tutorialspoint.com and Variable scope is a foretaste of object oriented programming, in the sense that it anticipates some encapsulation concepts. The search for the Ludolphine Part 1: Using the Clipper Tools (CT) Library If you checked the list of functions you will have noticed that the xBases have no trigonometric functions. Not that in general they miss them: these languages are targeted database applications such as 'accounting systems and airline reservations systems' (see. ) in which trigonometric functions are not really important.
But we now ask ourself how to compute an approximation to the Ludolphine number, π (more informations on this 'search' at ), We can do it using the CT library (see ), or importing the C standard library function atan. // we'll declare and load random numbers from 1 to 100 in an array DECLARE arrayToSort 12 FOR I = 1 TO 12 arrayToSort I = Int( HBRandom( 1,101 ) ) NEXT // we review our array FOR I = 1 TO 12?? ArrayToSort I NEXT // we'll do Exchange Sort as described in // where there is also a nice animation showing how it works!:) for i:= 2 TO Len(arrayToSort) for j:= Len(arrayToSort) TO i step -1 IF arrayToSort j - 1 arrayToSort j TEMP:= arrayToSort j - 1 arrayToSort j - 1:= arrayToSort j arrayToSort j:= TEMP ENDIF NEXT NEXT?? 'Sorted array:'?
// we look at our sorted array FOR I = 1 TO 12?? ArrayToSort I NEXT Here is our basis. We'll add a flag variable to improve this algorithm.
Database making Let's return to the Wikipedia entry. Different kinds of database applications exists as well. If you did store your friend's phone numbers and addresses into a word processor, you would have what is called a Free-Form Database (however, a similar expression is an oxymoron in computer science) - askSam is a specialized free-form database application. Now, a word processor lets us search the informations, but other operations, such as sorting them, cannot be done automatically by a word processor. What about attempting to store it into a spreadsheet? We may use one column for the name, one for the surname, one for the telefone number, one for the city. This quick database, stored in a spreadsheet, may be searched and sorted: for example we can sort it by city and person's name in alphabetical order.
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This is a flat database,: a flat database is a sequence of newline terminated records of delimiter separated fields, and a spreadsheet shows its limits in data entry and reporting (if you did want to use the data in your table to print out addresses on envelopes a spreadsheet is not a good tool). An example is MyDatabase. Spreadsheets are much better to do accounting: how much harder a book-keeper's work would be if his data were stored in a wordprocessing program? The purpose here is to have our data structured in a certain way: all the costs in a place, all earnings in another. Before 1970 complex databases where managed using Hierarchical Databases (very little information is needed about them - see for example and ). An example of a hierarchical database is IBM IMS (Information Management System, which was developed during the mid-1960s for applications in the aerospace industry).
Hierarchical Databases and Network Databases together form what today are referred to as Legacy Database Systems. Network databases where born as an extension to the programming language COBOL by the Conference on Data Systems Languages (CODASYL). Today's standard is a relational database, which is 'a database with relationships between more than one table of records based on common fields'. We will speak of them in detail, but we will briefly mention the fourth approach: Object Oriented Databases. These databases store objects (in the same sense the word is used in the expression object oriented programming).
They're not much used, mostly because object are more complex than the simple fields a relational database stores in its tables. Making a first database and recording some data A verbose way. CREATE TMPNAMES USE TMPNAMES APPEND BLANK REPLACE FIELDNAME WITH 'NAME' REPLACE FIELDTYPE WITH 'C' REPLACE FIELDLEN WITH 15 APPEND BLANK REPLACE FIELDNAME WITH 'ADDRESS' REPLACE FIELDTYPE WITH 'C' REPLACE FIELDLEN WITH 30 CLOSE CREATE NAMES FROM TMPNAMES && The code above created a DBF file, names.dbf, to be used by the following code. It will add a record to the DBF file. It is equivalent to the 'First Sample Program' of my old PC GUIDE, which missed a line that is necessary in modern xBase. 'First Sample Program' SELECT 1 USE NAMES APPEND BLANK REPLACE NAME WITH 'MIKE BROWN' REPLACE ADDRESS WITH 'ROME STREET, 56' CLOSE && this line is missing in my PC GUIDE but is needed QUIT The CLOSE command is equivalent to the dbCloseArea function, which closes a work area: Pending updates are written, pending locks are released.
A more concise way The short code below does the same work of the two pieces of code of the previous section (it only produces a different file name, namesdb.dbf instead of names.dbf). USE NAMES LIST DATE, TIME, NAME, ADDRESS Database Design Issue: the First Normal Form (1NF) The work done in the previous section was intended to exactly reproduce the database proposed in my PC GUIDE. There are, however, inconvenients: having only one NAME field, this database cannot sort its data on the last name. Also, a careless user might insert the data of some people with the last name first, and some other data with the first name last. When designing a database precautions should be taken of these possibilities. The first normal form (, ) requires you to define fields whose information cannot be divided into smaller parts.
So, instead of a NAME field, we should have a FIRSTNAME and LASTNAME fields. Complying to the first normal form, our little database would be on the on the right track to being a normalized database.
Complicating our simple database Harbour contains a file named test.dbf. Launch hbrun in its directory and type in use test browse At this point we see that it is a 500 record table. Move around with the cursor keys and, when you're finished, punch the Esc key to quit this interactive table browser and editor. To get the record number of a person called Ted issue: locate for first='Ted'?
Recno Here is the testdbf.prg source from hb30 tests. It should be discussed in detail. It is a GPL piece of code poorly commented. LASTREC DELETE RECORD 4 PACK? LASTREC In this piece of code the command DELETE marks the fourth record for deletion. But the file is not altered, not even by a CLOSE command.
The PACK command actually removes the records marked for deletion (and also makes some additional work). The RECALL command removes the deleted flags. The function DELETED returns.T. If the current record is marked for deletion,.F.
The PACK command, which does the actual deletion of data from the table, PACK requires that the current database be USEd EXCLUSIVEly. If this condition is not met when PACK is invoked, CA-Clipper generates a runtime error. Additional work that PACK does is to update indexes on the table it alters (if any). The commands DELETE ALL and PACK are executed by a single command called ZAP. Distance3d(1,1,1,4,4,4) FUNCTION distance1d( x1, x2 ) RETURN sqrt((x2-x1)^2) FUNCTION distance2d( x1,y1,x2,y2 ) RETURN sqrt((x2-x1)^2+(y2-y1)^2) FUNCTION distance3d( x1,y1,z1,x2,y2,z2 ) RETURN sqrt((x1-x2)^2+(y1-y2)^2+(z1-z2)^2) We defined three functions, with different names, which take as arguments the coordinates. But doing so we need to pass six arguments for the distance in a three-dimensional space.
If we're doing it with object oriented programming we may get something like this. FUNCTION Distance ( Point1, Point2 ) RETURN Sqrt( ( Point1:Abscissa - Point2:Abscissa ) ^ 2 + ( Point1:Ordinate - Point2:Ordinate ) ^ 2 + ( Point1:Zcoord - Point2:Zcoord ) ^ 2 )? Distance( FifthPoint, SixthPoint ) This is, however, not object-oriented programming, as we could have written the same function with a not object-oriented language such as Pascal or C, passing it two structs, or records as Pascal calls them, named Point1 and Point2. It is important the fact that some data internal to the object (set by the real programmer of the thing) can't be changed by the object user.
In real life an example is that of a car engine. The provider of the object set a number of cylinders, and we have not many chances of changing that: we've got to regard it as a constant. There is naturally a number of interesting formulas about engines that engineers use (some to be seen at ). For example the one for computing the Engine Volumetric Efficiency given the volume of air taken into a cylinder and the cylinder swept volume. Here comes the importance of data hiding: nobody needs to know those informations to get his car going. Also, when someone designes an engine they probably don't expect the user to change the volumetric efficiency by operating on the engine. The same thing is obtained in object oriented programming using visibility modifiers, or access modifiers.
CREATE CLASS FROM INHERIT.MODULE FRIENDLY STATIC FUNCTION HIDDEN: CLASSDATA CLASSVAR CLASS VAR DATA VAR AS INIT EXPORTED VISIBLE PROTECTED HIDDEN READONLY RO. METHOD ( ) CONSTRUCTOR METHOD ( ) IN LINE METHOD ( ) BLOCK METHOD ( ) EXTERN METHOD ( ) SETGET METHOD ( ) VIRTUAL METHOD ( ) OPERATOR ERROR HANDLER ( ) ON ERROR ( ). VISIBLE: EXPORTED:. FRIEND CLASS FRIEND FUNCTION SYNC METHOD ENDCLASS LOCK LOCKED Another example Copied verbatim from. #include 'hbclass.ch' PROCEDURE Main LOCAL oPerson CLS oPerson:= Pers on:New( 'Dave' ) oPerson:Eyes:= 'Invalid' oPerson:Eyes:= 'Blue' Alert( oPerson:Describe ) RETURN CREATE CLASS Person VAR Name INIT ' METHOD New( cName ) METHOD Describe ACCESS Eyes IN LINE::pvtEyes ASSIGN Eyes( x ) IN LINE iif( HBISSTRING( x ).AND. X $ 'Blue,Brown,Green',::pvtEyes:= x, Alert( 'Invalid value' ) ) PROTECTED: VAR pvtEyes ENDCLASS // Sample of normal Method definition METHOD New( cName ) CLASS Person::Name:= cName RETURN Self METHOD Describe CLASS Person LOCAL cDescription IF Empty(::Name ) cDescription:= 'I have no name yet.' ELSE cDescription:= 'My name is: ' +::Name + ';' ENDIF IF!
Empty(::Eyes ) cDescription += 'my eyes' color is: ' +::Eyes ENDIF RETURN cDescription Harbour CGI and see the side box.
Contents. History Clipper was created by, a company that was started in 1984 by Barry ReBell (management) and Brian Russell (technical). In 1992, the company was sold to for 190 million dollars and the product was renamed to CA-Clipper. Clipper was created as a replacement for 's III, a very popular at the time. The advantage of Clipper over dBASE was that it could be and under as a. In the years between 1985 and 1992 millions of Clipper applications were built, typically for small businesses dealing with databases concerning many aspects of and.
For many smaller businesses, having a Clipper application designed to their specific needs was their first experience with software development. Also a lot of applications for and were developed, here especially in those cases where the application was considered too small to be developed and run on traditional. In these environments Clipper also served as a for existing mainframe applications. As the product matured, it remained a tool for many years, but added elements of the and, as well as, and the code-block (hybridizing the concepts of dBase, or -evaluation, and ), to become far more powerful than the original. Nantucket's Aspen project later matured into the native-code compiler. Decline Despite these efforts in the early nineties under its new ownership Clipper proved to be unable to make a smooth transition from the to the era.
As a result, almost no new commercial applications were written in Clipper after 1995. Three of the more important languages that took over from Clipper were, and. Some existing Clipper applications continued in use for ten or fifteen years, requiring regular maintenance, but around 2015 the number of Clipper applications that were still used commercially on a daily basis was very small.
Revival by third-parties The Clipper language is being actively implemented and extended by multiple organizations/vendors, like from Alaska Software and, as well as (-licensed) projects like and. Many of the current implementations are portable (, ( and ), (32- and 64-bit), and ), supporting many language extensions, and have greatly extended, as well as various Replaceable Database Drivers (RDD) supporting many popular database formats, like, DBTNTX, DBFCDX (, Apollo, Comix, and Advantage Database Server), MachSix (SIx Driver and Apollo), and more.
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These newer implementations all strive for full compatibility with the standard / syntax, while also offering OOP approaches and target-based syntax such as SQLExecute. Usenet The Clipper are and. Compiling and running hello world program in clipper Programming in Clipper A simple - application:? 'Hello World!'
. GrafX Software licensed CA-Clipper in 2002 from CA for ongoing marketing and distribution.
dBASE code changes it from interpreted code, which must be every time each line of code is executed, to, which uses a to process the compiled p-code. P-code is considerably faster, but still not as fast as the generated by native compilers. As a technical marketing ploy, the p-code was wrapped into object code (linkable.obj files) which gave the impression that it was compiled to native code. The History Of Computing Project. 20 June 2007. External links.
vendor of. article. is the largest file archive for CA-Clipper and xBase on the web.
Integrated development environment for Windows. A 32/64 bit multiplatform Clipper compiler. How to install Harbour MiniGUI and compile a windows-exe.:Active web pages using server-side Xbase scripts, embedded DBF data engine, freeware, based on MaxScript Xbase interpreter (adds xBase/Clipper server-side scripting to IIS / Apache / Xitami web servers).:the Xbase interpreter for desktop and web applications., WIN32 Gui Framework for (x)Harbour, backward compatible with Clipper and Clip4Win., CA Clipper programming language history and overview.
On Saturday January 24, 2015 ouhker said: Microsoft C 5.1 was used to develop Clipper 5. (not 5.3) However, Clipper 5.2 does not have math functions, e.g. Sin(x), cos(x), tan(x), log(x). To use math functions in clipper 5.2 you have to use MicroSoft C5.1 to write a wrapper function, and link with the (MSC5.1) 'alternate math library' (llibca.lib). During the installation of MSC 5.1 you have the option of building (80x87) 'emulation' library, 'float point' library and 'alternate math' library. Choose 'yes' for 'alternate math'.
Turbo C 2.01 can compile but NEVER links.
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