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In computing, a compiler is a computer program that transforms source code written in a programming language or computer language (the ''source language''), into another computer language (the ''target language'', often having a binary form known as ''object code'' or ''machine code''). The most common reason for wanting to transform source code is to create an executable program. Any program written in a high level programming language must be translated to object code before it can be executed, so all programmers using such a language use a compiler or an interpreter. Thus, compilers are very important to programmers. Any improvement to a compiler leads to a large number of improved executable programs. Compilers are large and complex programs, but systematic analysis and research by computer scientists has led to a clearer understanding of compiler construction and a large body of theory has been developed around them. Research into compiler construction has led to tools that make it much easier to create compilers, so that today computer science students can create their own small language and develop a simple compiler for it in a few weeks. == First compilers == Software for early computers was primarily written in assembly language. It is usually more productive for a programmer to use a high-level language, and programs written in a high-level language can be reused on different kinds of computers. Even so, it took a while for compilers to become established, because they generated code that did not perform as well as hand-written assembler, they were daunting development projects in their own right, and the very limited memory capacity of early computers created many technical problems for practical compiler implementations. The first compiler was written by Grace Hopper, in 1952, for the A-0 System language. The term ''compiler'' was coined by Hopper.〔Maurice V. Wilkes. 1968. Computers Then and Now. Journal of the Association for Computing Machinery, 15(1):1–7, January. p. 3 (a comment in brackets added by editor), "(I do not think that the term compiler was then () in general use, although it had in fact been introduced by Grace Hopper.)"〕〔() The World's First COBOL Compilers 〕The A-0 functioned more as a loader or linker than the modern notion of a compiler. The first autocode and its compiler were developed by Alick Glennie in 1952 for the Mark 1 computer at the University of Manchester and is considered by some to be the first compiled programming language. The FORTRAN team led by John W. Backus at IBM is generally credited as having introduced the first complete compiler, in 1957. The first FORTRAN compiler took 18 person-years to create.〔Backus et al. "The FORTRAN automatic coding system", Proc. AFIPS 1957 Western Joint Computer Conf., Spartan Books, Baltimore 188–198〕 The first ALGOL 58 compiler was completed by the end of 1958 by Friedrich L. Bauer, Hermann Bottenbruch, Heinz Rutishauser, and Klaus Samelson for the Z22 computer. Bauer et al. had been working on compiler technology for the ''Sequentielle Formelübersetzung'' (i.e. ''Sequential Formula Translation'') in the previous years. By 1960, an extended Fortran compiler, ALTAC, was available on the Philco 2000, so it is probable that a Fortran program was compiled for both IBM and Philco computer architectures in mid-1960.〔() Rosen, Saul. ''ALTAC, FORTRAN, and compatibility''. Proceedings of the 1961 16th ACM national meeting〕 The first known demonstrated cross-platform high-level language was COBOL. In a demonstration in December 1960, a COBOL program was compiled and executed on both the UNIVAC II and the RCA 501.〔 The COBOL compiler for the UNIVAC II was probably the first to be written in a high-level language, namely FLOW-MATIC, by a team led by Grace Hopper. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「History of compiler construction」の詳細全文を読む スポンサード リンク
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