C Theory

Theory on C language

1. C language

2. Consists of a set of predefined rules. These rules form the syntax of that language. Hence learning a programming language is nothing but learning of that language. Introduction of c language

3. Computer can understand only instructions written in binary code ( 0 and 1), They do not directly read or understand a any programming language. And so a programming language is converted into binary code by using a special program called compiler. A program which translates instructions written in a programming language into binary code is called a compiler. When we write a program in C Language, what we write is called Source Code. The compiler’s output is called executable code . compiler

4. C is a programming language developed at AT&T Bell laboratories around 1972. It was designed and written by Dennis M. Ritchie . C was standardized in 1989 by American National Standard Institute (ANSI) . So it came to be known as ANSI C. C is a structured language. It breaks up a program into small parts known as functions . history

5. Flow chart use to define flow of any program. symbolic representation of program. use different symbols. Basic programming techniques

6. Rectangle Parallelogram Diamond Lines oval Symbols

7. Use to define process in program Rectangle

8. Use to define input and output in program Parallelogram

9. Use to specify condition in program Diomand

10. To show flow of the program lines

11. Use to declare start and end of flow chart and connect flow chart with other flow chart pages also. connector

12. start end Input output output condition Process if true Process if false

13. start end Insert value of i Print value of I is less than five Print value of I is greater than five If( i <5) Declare variable I as integer

14. Documentation Symbolic Constant Definition File Include Section Global Variable Declaration Main() { Declaration Executable Statements } Function 1 Function 2 Function n…. Structure of c program starting Section Compulsory section for all C Programs User Defined Functions

15. Compile is one type of program to convert source code into machine level code, Compiler compile the code of block and return the error and warning list. Compiler

16. #include < stdio.h > #include < conio.h > void main() { printf (“My first program”); getch (); } My first program in c language

17. #include < stdio.h > #include < conio.h > # : is pre possessive directive. use to include header files before start the program. Explanation of program

18. Header file is collection of pre define functions. Extension of header file is must “ .h ”. Header files are located in “INCLUDE” folder of “TC ”. Header files

19. void main() { main() c compile founds main() to start execution of program. must declare main function in every program. Explanation cont…

20. { braces use to define starting of coding block. Explanation cont…

21. printf (“My First program”); printf () : use to print any formatted string in output window of Turbo c. header file : stdio.h ( standard input output ) Explanation cont…

22. getch (); } getch () use to get 1 character from keyboard. } define end of coding block. Explanation cont…

23. Compile the source code with. Alt + F9 Run the program with. Crtl + F9 How to run ?????

24. C language is totally case sensitive language. All the statements of C language must terminate with semi colon ( ; ) Must Remember

25. My First program Output of first program

26. file type extension C- Source file .C application file .EXE object file .OBJ Back ground files

27. Comment lines ignore by c compiler // use for single line comment /* */ use for multiline comment Comments in c languages

28. Integer Float Double Character Basic data types

29. Signed integer range -32,768 to 32,767 occupy first bit as a sigh bit. ( + / - ) memory space ( 2 bytes ) Integer

30. Unsigned integer range 0 to 65,535 not occupy any bit as sign bit. memory space ( 2 bytes ) Note : to declare unsigned integer variable must use unsigned key word before integer. Integer cont…

31. Use to store values with fiction point. memory space ( 4 bytes) 32 bits Double 64 bits(8 bytes) Long double 80 bits(10 bytes) Float

32. Default unsigned character 8 bits ( 1 byte ) Range : 0 to 255 Signed character 8 bits ( 1 byte ) Range : -128 to 127 Character

33. int a = 10; printf (“Value of variable a is : % d”,a ); o/p : Value of variable a is : 10 Print formatted output

34. %d use for integer values %f use for float values %c use for character %s use for String %l use for double values %lf use for long double values Other format strings

35. Use scanf () function Syntax : scanf (“format character ”, &variable name); Get values from user.

36. int a; printf (“Enter value of a ”); scanf (“% d”,&a ); printf (“Value of variable a is : % d”,a ); o/p value of variable a is : 10 Note : assume that we entered 10 from keyboard. example