Report

Abstract

The language PASCAL has now been in use for several years, during which considerable experience has been gained through its use, its teaching, and its implementation. Although many reasons suggest that a language should be kept unchanged as soon as it has gained a user community, it would be unwise to ignore this experience and to refrain from making good use of it. This Report therefore describes a revised language which included some changes suggested by the work of the last two years. It is still of the form of the original definition, and in fact the changes are very few and relatively minor. They concern the following subjects:

• Constant parameters are replaced by value parameters (in the sense of Algol 60).

• The class structure is eliminated: pointer variables are bound to a data type instead of a class variable.

• The handling of files is changed such that the buffer variable f↑ always has e defined value except when the condition eof(f) is true.

• Packed records and packed arrays are introduced. As a consequence, the type alfa becomes a special case of a packed character array. The generalization has some consequences on the denotation of strings (formely called alfa constants).

• Programs require a program heading with external files as parameters.

• All labels require a declaration.