Character set, variables, constants and keywords Character set: Character set contains alphabets, numbers, and symbols for representing information. Following set shows characters used in C: Alphabets A,B,C,D……………X,Y,Z A,b,c,d…………….x,y,z Numbers 0,1,2,3,4,5,6,7,8,9 Special Symbols ?></.,;’:”[]{}\|*-+_()*&^%$#@! Variables: Variable is an entity which can change or it is a name of the memory location. It should start with only alphabets or underscore. Also called identifiers. e.g. int A=10; consider memory location 1000 in a computer’s memory where 10 value is stored. So we can retrieve or modify value 10 through variable A. Constants: Constant is an entity which cannot change. e.g. int A=10; 10 is a constant. Types of constants: 1.Primary Constants 2.Secondary Constants Constants Range Integer -32768 to +32767 Float -3.4e38 to
Let's start with the history of C Before beginning with programs in C, it would be interested to know the history of it. C language is invented by Dennis Ritchie at bell laboratories of AT and T in the USA. It is invented in 1972. Dennis Ritchie is known as the founder of C language. Initially, C is developed for the UNIX operating system, then it is used in applications. In the late seventies, it replaces more familiar languages like PL/I, ALGOL, etc. C seems so popular is because it is reliable, simple, and easy to use. Moreover, in industry newer languages, technologies come and vanish all day out, a language that is survived for three decades is C.Let's see the programming languages that were developed before the C language. Language Year Developed By Algol 1960 International Group BCPL 1967 Martin Richard B 1970 Ken Thompson C 1972 Dennis Ritchie