start programing

Hi this is hemant behera's blog for programming.so we should start with "c ",The mother of programming....
C Basics Before we embark on a brief tour of C's basic syntax and structure we offer a brief history of C and consider the characteristics of the C language.
In the remainder of the Chapter we will look at the basic aspects of C programs such as C program structure, the declaration of variables, data types and operators. We will assume knowledge of a high level language, such as PASCAL.
It is our intention to provide a quick guide through similar C principles to most high level languages. Here the syntax may be slightly different but the concepts exactly the same.
C does have a few surprises:
Many High level languages, like PASCAL, are highly disciplined and structured.
However beware -- C is much more flexible and free-wheeling. This freedom gives C much more power that experienced users can employ. The above example below (mystery.c) illustrates how bad things could really get.
History of C
The milestones in C's development as a language are listed below:
UNIX developed c. 1969 -- 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. 1970.
A totally new language ``C'' a successor to ``B''. c. 1971
By 1973 UNIX OS almost totally written in ``C''.
Characteristics of C
We briefly list some of C's characteristics that define the language and also have lead to its popularity as a programming language. Naturally we will be studying many of these aspects throughout the course.
Small size
Extensive use of function calls
Loose typing -- unlike PASCAL
Structured language
Low level (BitWise) programming readily available
Pointer implementation - extensive use of pointers for memory, array, structures and functions.
C has now become a widely used professional language for various reasons.
It has high-level constructs.
It can handle low-level activities.
It produces efficient programs.
It can be compiled on a variety of computers.
Its main drawback is that it has poor error detection which can make it off putting to the beginner. However diligence in this matter can pay off handsomely since having learned the rules of C we can break them. Not many languages allow this. This if done properly and carefully leads to the power of C programming.
As an extreme example the following C code (mystery.c) is actually legal C code.
#include
main(t,_,a)
char *a;
{return!0main(-86, 0, a+1 )+a)):1,t<_?main(t+1, _, a ):3,main ( -94, -27+t, a
)&&t == 2 ?_<13 ?main ( 2, _+1, "%s %d %d\n" ):9:16:t<0?t<-72?main(_,
t,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l,+,/n{n+\
,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/\
+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){n\
l]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#\
n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c \
;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;\
#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/")
:t<-50?_==*a ?putchar(a[31]):main(-65,_,a+1):main((*a == '/')+t,_,a\
+1 ):0ek;dc \
i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry"),a+1);}
It will compile and run and produce meaningful output. Try this program out. Try to compile and run it yourself. Alternatively you may run it from here and see the output.
Clearly nobody ever writes code like or at least should never. This piece of code actually one an international Obfuscated C Code Contest http://reality.sgi.com/csp/iocc The standard for C programs was originally the features set by Brian Kernighan. In order to make the language more internationally acceptable, an international standard was developed, ANSI C (American National Standards Institute).
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
We must have a main() function.
A function has the form:
type function_name (parameters)
{
local variables

C Statements

}
If the type definition is omitted C assumes that function returns an integer type. NOTE: This can be a source of problems in a program.
So returning to our first C program:
/* Sample program */

main()
{

printf( ``I Like C n'' );
exit ( 0 );

}
NOTE:
C requires a semicolon at the end of every statement.
printf is a standard C function -- called from main.
n signifies newline. Formatted output -- more later.
exit() is also a standard function that causes the program to terminate. Strictly speaking it is not needed here as it is the last line of main() and the program will terminate anyway.
Let us look at another printing statement: printf(``.n.1n..2n...3n'');
The output of this would be:
.
.1
..2
...3