Compared anatomy of the programming languages Pascal and C

Abstract

The programming languages PASCAL and C belong to the class of algorithmic compiled languages, and feature comparable facilities. The syntax of C is more regular and enjoys less restrictions than that of PASCAL. Consequently, the syntax of C is significantly simpler than that of the PASCAL language. The design differences are particularly apparent as far as data types, operators, and system interface are concerned. PASCAL implements abstract data types (booleans, sets), whereas C defines data types that reflect the architecture of currently available computers. For PASCAL, the system interface is implemented via functions built in the language and is therefore not extensible by the user. Most of the practical implementations of the language require non standard extensions. In C, system calls and libraries of subroutines and macro instructions are provided to handle the system interface. The portability of applications then depends on the libraries and not on the compiler. A greater flexibility is thus achieved. The use of pointers and the rich set of operators of the C language make it more general than PASCAL, while retaining the principles of structured programming. Separate compilation is a standard feature of C, not of PASCAL. PASCAL compilers are often complex, while C compilers are simple and compact. C compilers include a macro processor, and the program verifier is a separate tool. The application programmers have more responsibility programming in C than in PASCAL, conversely, applications depend less on compilers in C than in PASCAL.