1. C Programming language
" ‘white book’ or ‘K&R’ "

2. C Language Programming History
UNIX developed c DEC PDP-7 Assembly Language.
BCPL -- a user friendly OS providing powerful development tools developed from BCPL. Assembler tedious long and error prone.
A new language ``B'' a second attempt. c
A totally new language ``C'' a successor to ``B''. c
By 1973 UNIX OS almost totally written in ``C''.

3. C Language Design Goals
It to be compiled using a relatively straightforward compiler.
Provide low-level access to memory.
Provide language constructs that map efficiently to machine instructions.
Require minimal run-time support.
C was therefore useful for many applications that had formerly been coded in assembly language.

4. C Language Characteristics
C has facilities for structured programming and allows lexical variable scope and recursion.
Parameters of C functions are always passed by value.
Pass-by-reference is achieved in C by explicitly passing pointer values.
C program source text is free-format, using semicolon as a statement terminator (not a delimiter).

5. More Specific Characteristics
Non-nestable function definitions, although variables may be hidden in nested blocks.
Partially weak typing; for instance, characters can be used as integers.
Array indexing as a secondary notion, defined in terms of pointer arithmetic.
Function pointers allowing for a rudimentary form of closures and runtime polymorphism.

6. C Program Structure A C program basically has the following form :
Preprocessor Commands
Type definitions
Function prototypes -- declare function types and variables passed to function.
Variables
Functions

7. C language Function C programming must have a main() function.
A function has the form :
type function_name (parameters) {
local variables   C Statements }

8. C Language Variables C has the following simple data types :
To declare a variable in C, do :
    var_type list variables;

9. Defining Global Variables
Global variables are defined above main() in the following way
Example :
short number,sum;
int bignumber,bigsum;
char letter;
  main() {   }

10. Printing Out and Inputting Variables
C uses formatted output. The printf function has a special formatting character (%) -- a character following this defines a certain format for a variable :
%c -- characters %d -- integers %f -- floats    
e.g. printf(``%c %d %f'',ch,i,x);
Scanf() is the function for inputting values to a data structure: Its format is similar to printf :
i.e. scanf(``%c %d %f'',&ch,&i,&x);

11. Using C Language Programming
C's primary use is for "system programming", including implementing operating systems and embedded system applications.
C has also been widely used to implement end-user applications.
C source code is then input to a C compiler, which then outputs finished machine or object code.
One consequence of C's wide acceptance and efficiency is that the compilers, libraries, and interpreters of other higher-level languages are often implemented in C.