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Programming In C

Programming in C
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Programming in C
Prof. Gustavo Alonso Computer Science Department ETH Zürich alonso@inf.ethz.ch http://www.inf.ethz.ch/department/IS/iks/

A brief history of C C as a programming language C Programming "main function "constants, variables, data types "operators, control structures "functions "data structures "pointer arithmetic "structures "dynamic memory allocation

©Gustavo Alonso, ETH Zürich.

Programming in C 2

A brief history of C
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C as a programming language
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Programming languages are used to specify, design, and build software systems. Programming languages evolve with the systems they are used to construct. C is a good example of how this process takes place. UNIX was developed at around 1969. It first version was programmed in assembler and run on a DEC PDP-7. The second version was ported to a PDP-11 in 1971 and it was a great success: "16 KB for the system "8 KB for user programs "disk of 521 KB "limit of 64 KB per file

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While writing a FORTRAN compiler for UNIX, a new programming language was developed: B B was interpreted (like Java) and, therefore, slow. To solve the performance problems of B, a new language was created: C "allowed generation of machine code (compilation) "declaration of data types "definition of data structures In 1973 UNIX was rewritten in C something that was never done before "C is much easier to handle than assembler but "first C version of UNIX was 20 to 40 % larger and slower than assembler version
Programming in C 3

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C has been standardized (ANSI C) and spawned new languages (C++, Stroustrup, 1986) that improve C The basic characteristics of C are: "small in size "loose typing (lots of freedom, error prone) "structured (extensive use of functions) "designed for systems programming (i.e., low level programming of the type needed to implement an operating system) "C is higher level than assembler but still close to the hardware and allows direct...