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Write once, compile anywhere (WOCA) is a philosophy taken by a compiler and its associated software libraries or by a software library/software framework which refers to a capability of writing a computer program that can be compiled on all platforms without the need to modify its source code. As opposed to Sun's write once, run anywhere slogan, cross-platform compatibility is implemented only at the source code level, rather than also at the compiled binary code level.
There are many languages that follow the WOCA philosophy, such as C++, Pascal (see Free Pascal), Ada, Cobol, or C, on condition that they don't use functions beyond those provided by the standard library. Languages like Go go even further in as far that no system specific things are used, it should just work, and for system-specific elements a system of platform-specific files is used. A computer program may also use cross-platform libraries, which provide an abstraction layer hiding the differences between various platforms, for things like sockets and GUI, ensuring the portability of the written source code. This is, for example, supported by Qt (C++) or the Lazarus (Pascal) IDE via its LCL and corresponding widgetsets.
Today, we have very powerful desktop computers as well as computers in our phones, which often have sophisticated applications such as word processing, Database management, and spreadsheets, that can allow people with no programming experience to, sort, extract, and manipulate their data. and create documents (such as PDF files) showing their now organized information, or printing it out. Before 2000, some of these were not available, and prior to 1980, almost none of them were.
From the start of computer automation in the early 1960s, if you wanted a report from data you had, or needed to print up invoices, payroll checks, purchase orders, and other paperwork businesses, schools and governments generated, you typed them up on a physical typewriter, possibly using pre-printed forms. Otherwise, if you did have information stored in a computer, and wanted it sorted, manipulated, or printed, it required someone to write a program to do so. In some cases, the person needed information that professional programmers either could not understand how to provide a program to do what they wanted; the available programmers could not produce something in a reasonable amount of time; or there weren't any programmers they could use, caused some non-programming professionals to learn some programming skills, at least to know how to manipulate and print out information they needed from their data.
Whether the work was done by a professional programmer, or an end-user writing a program to provide them information for their own use, the means to do this in either case is the same. Write a program, submit it to a compiler (another program that converts written programs into instructions the computer can understand), fix any errors, then repeat until the program worked.
While this helped fix part of the problem, it created a new one. People who wrote programs, or hired someone to write them (purchasing software was not a thing until the 1970s or 1980s), discovered when their employer or school bought a new computer, their programs no longer worked.
Originally, programming at the written level was done by writing programs in assembly language. The problems with this are that
To combat these problems, various high-level languages were developed that were usable for general purpose application program development, but could be used to provide reports and information for people with specialized requirements.
These include:
While compilers and interpreters of all of these languages, and dozens of others, were available for different machines and different vendors, often each manufacturer would develop proprietary enhancements which made programing on that machine easier, but again, made programs difficult to port (move the program to a different type of computer or a different vendor's computers), and increased vendor lock in. Something had to change.
Starting in the late 1960s and early 1970s, efforts came into play to create standards and specifications of how machine-independent programs could be written using compilers from any vendor. Standards-making organizations, like the International Standards Organization (ISO), and ANSI, among others, in cooperation with large users of computers and software (like governments, financial institutions and manufacturers), and computer manufacturers, to create standardized specifications to provide a description of how each specific language should be implemented.
Computer manufacturers could still have their own proprietary extensions to a programming language, but if they wanted to be able to claim compliance with the standard, they had to specify the differences in the reference manual, so that a program written according to the standard able to compile and operate on their machine would also operate, without further change, on a different manufacturer's computer whose compiler also followed the standard. The requirements of the standard were enforced by large software buyers, such as military, government, and manufacturing companies, by refusing to buy such computing equipment if the vendor only offered a compiler for the programming languages they used which wasn't compliant with the standard,
Currently, there are more than a dozen programming languages that have standards describing how programs in the language are supposed to be written, including Ada, APL, BASIC, C++, COBOL, ECMAScript (the generic name for JavaScript), Forth, FORTRAN, Pascal, PL/I, Ruby and SQL. Many of these are still in use, in some cases, because customers were able to take their source code to a different manufacturer's computer, where it was recompiled, often without change, because of the standardization of programming languages.
While the standards helped, the WOCA philosophy works only when the makers of compilers ensure that they follow the standard.
In computer programming, assembly language, often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence between the instructions in the language and the architecture's machine code instructions. Assembly language usually has one statement per machine instruction (1:1), but constants, comments, assembler directives, symbolic labels of, e.g., memory locations, registers, and macros are generally also supported.
Computer programming is the process of performing particular computations, usually by designing and building executable computer programs. Programming involves tasks such as analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms. The source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, which is directly executed by the central processing unit. The purpose of programming is to find a sequence of instructions that will automate the performance of a task on a computer, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algorithms, and formal logic.
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A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
PL/I is a procedural, imperative computer programming language developed and published by IBM. It is designed for scientific, engineering, business and system programming. It has been used by academic, commercial and industrial organizations since it was introduced in the 1960s, and is still used.
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In computer science, a pointer is an object in many programming languages that stores a memory address. This can be that of another value located in computer memory, or in some cases, that of memory-mapped computer hardware. A pointer references a location in memory, and obtaining the value stored at that location is known as dereferencing the pointer. As an analogy, a page number in a book's index could be considered a pointer to the corresponding page; dereferencing such a pointer would be done by flipping to the page with the given page number and reading the text found on that page. The actual format and content of a pointer variable is dependent on the underlying computer architecture.
Write once, run anywhere (WORA), or sometimes Write once, run everywhere (WORE), was a 1995 slogan created by Sun Microsystems to illustrate the cross-platform benefits of the Java language. Ideally, this meant that a Java program could be developed on any device, compiled into standard bytecode, and be expected to run on any device equipped with a Java virtual machine (JVM). The installation of a JVM or Java interpreter on chips, devices, or software packages became an industry standard practice.
In computer science, automatic programming is a type of computer programming in which some mechanism generates a computer program to allow human programmers to write the code at a higher abstraction level.
KDF8 was an early British computer built by English Electric as a version of the RCA 501. By producing a software-compatible system, the intention was to reduce time and cost to develop software. However, the lengthy process of developing manufacturing capability meant that the system was soon outpaced by systems from other vendors. Only a few systems were sold during its 5 years of production. Due to the consolidation of the British computer industry, English Electric's computer division became one of the components of what would become ICL.
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