1 Programming in Oberon

2 Preface This text is an introduction to programming in general, and a guide to programming in the language Oberon in particular. It is primarily oriented towards people who have already acquired some basic knowledge of programming and would like to deepen their understanding in a more structured way. Nevertheless, an introductory chapter is added for the benefit of the beginner, displaying in a concise form some of the fundamental concepts of computers and of programming them. The text is therefore also suitable as a self-contained tutorial. The notation used is Oberon, which lends itself well for a structured approach and leads the student to a working style that has generally become known under the heading of structured programming. As a manual for programming in Oberon, the text covers (almost) all facilities of this language. Part 1 covers the basic notions of variable, expression, assignment, conditional and repeated statement, and the data structure of the indexable array. Together with Part 2, which introduces the important concept of the procedure or subroutine, it contains essentially the material commonly discussed in introductory programming courses. Part 3 concerns data types and structures and constitutes the core of an advanced course on programming. Part 4 introduces the notion of a module, a concept that is fundamental in the design of large programming systems, and to programming in teams. The two basic notions of files and texts are introduced in the forms of modules containing the operations performed on files and texts. Texts are presented as our standard medium for program input and output. was designed by an international committee of 13 scientists, and it was the first language to be specified with a rigorous formalism, a syntax, in machine-independent form. Algol was largely oriented toward numerical algorithms, as were computers at that time. Pascal [2] was the result of an enduring debate about widening the range of application of Algol, and it became widely used, in particular but not only, in education. Modula-2 [3] introduced the concept of modules, the parts of large systems connected by clearly specified interfaces. The module allows to hide details of procedures and variables from its users (clients), and it embodies the principle of information hiding. The language Oberon [4] emerged from the urge to reduce the complexity of programming languages, of Modula in particular. This effort resulted in a remarkably concise language. The extent of Oberon, the number …