1. OVERVIEW OF ‘C’ PROGRAM
BY
SAHITHI NARAPARAJU

2. INTRODUCTION

C was introduced by “Dennis M ritche” in 1978.

C is a structured programming language.

C is portable language this means that C programs written for
one computer can be run on another computer with little
modification or no modification.

Another important feature of C is its ability to extend.

3. 
C program is basically collection of functions that are
supported by C library. We can continuously add our own
functions to C library.

The C compiler combines the capabilities of an assembly
language with the features of a high-level language.

Programs written in c are efficient and fast. This is due to its
variety of data types and powerful operators.

4. 
Sample C program:
main()
{
/*…………….. printing begins………………*/
printf (“Hello how r u?”);
/* ……………………printing ends……………….*/
}

Output of the program is : Hello how r u?

Main() is a special function used by C to tell the compiler
where the program starts.

Every program must have exactly one main function.

5. 
If we use morethan one main function, compiler cannot
understand which one marks beginning of the program.

The empty pair of parentheses followed by main function
indicates that the function has no arguments.

The opening brace “ { ” marks the beginning of the main
function and closing brace “}” indicates end of the function.

All statements between “{ ” and “}” these braces form
function body.

Function body contains set of instructions to perform the given
tasks.

6. 
The function body contains 3 statements out of which only the
printf line is an executable statement.

The lines beginning with /* and ending with */are known as
comment lines.

Comment lines are not executable statements.

A C program can be viewed as a group of building blocks
called functions.

A function is a subroutine that may include one or more
statements designed to perform a specific tasks.

7. AN OVERVIEW OF C PROGRAM
A C program consists of following sections:
a) Documentation section
b) Link section
c) Definition section
d) Global declaration section
e) main function section
e) subprogram section

2)
Main function consists of 2 parts namely:
Declaration part and
Executable part

Subprogram section contains all the user defined functions.

1)

8. Documentation section
Link section
Definition section
Global declaration section
main() function section
{
Declaration part
Executable part
}
Sub program section
Function 1
Function 2
user defined function
….
Function n

9. 
Documentation section consists of a set of comment lines
giving the name of the program, the author and other details
which programmer would like to use later.

Link section provides instructions to the compiler to link
function from the system library.

Definition section defines all symbolic constants.

Every C program must have one main() function section.

The section contains 2 parts declaration part and executable
part.

10. 
Declaration part declares all variables used in executable part.

The 2 parts must appear between opening and closing braces.

All statements in declaration and executable parts end with
semicolon (;).

The subprogram section contains all the user-defined functions
that are called in main function.

User-defined functions are generally placed immediately after
main function, although they may appear in any order.

11. EXECUTING A C PROGRAM

Executing a program written in C involves a series of steps.

These are 4 steps involved in executing a C program:
Creating the program.
Compiling the program.
Linking the program with functions that are needed from the
C library.
Executing the program.
1)
2)
3)
4)