Overview, History, Features, Advantages and Disadvantages of C language
4.1 Introduction
Overview, History, Features, Advantages and Disadvantages of C language
Overview of C Language
The C language is one of the most
powerful languages. In the beginning due to the different architectures
available, the programmer had to learn different languages to create different
types of applications. The problem with low level languages is that they are
very difficult for humans to understand and develop. On the other hand, High
Level Languages are easy for humans to understand.
The C language is a highly efficient
programming language and easy to understand. It has both the properties of high
level language and low level language, so it is also termed as Middle Level
Language or intermediate language between high level language and low level
language. It is a very powerful programming language because it is used to
prepare system software as well as application software. It is a kind of
general purpose, structured programming language. It has large numbers of
vocabularies and simple syntax to write a program.
History of C
Language
C is a general purpose programming
language. C language was designed and developed by Dennis Ritchie at Bell
Laboratories in 1972. It is an offspring of the "Basic combined
programming language" called BCPL developed in the year 1967 at
Massachusetts Institute of Technology. This language is associated with the
UNIX operating system. The source code for the UNIX operating system is coded
in C. It runs under a number of operating systems including MS DOS. C programs
are efficient, fast and highly portable programming language. The C language is
named as C because its precedence was called B which was derived from BCPL by
Ken Thompson in 1970 in Bell Labs. The development of UNIX in the C language
made it uniquely portable and improvable.
POINTS TO REMEMBER
|
|
C
is a general purpose, portable, compact, simple and flexible programming
language. |
Features of C Language
C Language is a very popular language because it has large
numbers of features for programmers to write medium types of programs. Some
basic features of C language are given below.
●
It is highly portable Language
●
It is a structured programming language because the program
is divided into a number of functions.
●
It is a general purpose high level programming language.
●
It is an internationally standardized programming language.
●
It has both the features of high level languages as well as
low level languages.
Advantages
of C Language
●
It is easy for debugging, testing and maintaining.
●
It is a portable programming language. This means a program
written for one computer may run successfully on another computer.
●
It is fast for executing. This means that the executable
program obtained after compiling and linking runs very fast.
●
It is a compact programming language. The statements in C
language are generally short but very powerful.
●
It has only 32 Keywords so that's easy to remember.
●
Its compiler is easily available.
●
It has the ability to extend itself. Users can add their own
functions to the C library.
Disadvantages
of C Language
C programming language has no strong disadvantages. But it
has some negligible disadvantages that are given below.
●
There is no runtime checking.
●
There is no strict type checking (for example we can pass an
integer value for the floating data type).
●
As the program extends it is very difficult to fix the bugs.
●
It may compile time overhead due to the misplacing and
excessive use of pointers.
●
It does not support modern programming approaches like
object oriented programming.
1.
List out features of C programming language.
2.
List out advantages and disadvantages of C programming
language.
Structure of
C Program
Every C program contains a number of several building blocks
known as functions. Each function performs tasks independently. The structure
of C program is given below.
/* Comments * /
Preprocessors and Header
Files
Function header
Global Declaration
void main()
{
Declaration part
Executable part
}
User defined functions
{
Body of user defined
functions
}
Header Files
C program depends upon some header files for function
definition that are used in the program. Each header file by default is
extended with h. The file should be included using #include pre-processor
directive. Example is given below.
#include<stdio.h>
Global
Declaration
It declares some variables that are used in more than one
function. These variables are known as global variables.
void main()
Every program of C language must contain the main ()
function. The main () is the starting point of every C program.
Declaration
Part
It declares the variables that are used inside this
particular function. The initialization of variables are also done in this
section.
Executable
Part
This part contains the statement blocks that may be input
statement, process statement and output statement.
User defined
functions
The functions defined by the user are called user defined
functions. These functions are defined before or after the main() function.
Comments
It is not necessary in the program. However, to understand
the flow of programs the programmer can include comments in a program.
Function
header
It defines the heading or prototypes of the functions.
Example
Compiling
Process
Step 1 Use a text editor like notepad to
write your source code and save the file with extension dot c. For example:
abc.c
Step 2 Compile the program using a
compiler. If the compiler doesn't find any errors in the program, it produces
an object file with .obj extension and the same name as the source code file
(for example, test.c compiles to test.obj). If the compiler finds errors, it
reports them. We must return to step 1 to make corrections in your source code.
Step 3 Link the program using a linker. If
no errors occur, the linker produces an executable program located in a disk
file with .exe extension and the same name as the object file (for example,
test.obj is linked to create test.exe)
Step 4 Execute the program. We should test
to determine whether it functions properly. If not, start again with step 1 and
make modifications and additions to your source code.
Your First C
Program
This demonstration uses a program named hello.c, which
displays the words ‘Hello, World!’ on-screen. The source.code for hello.c is
given below.
Example: Simple program showing ‘Hello
World’.
1: #include
<stdio.h>
2: void main()
3: {
5: printf("Hello,
World\n");
5: }
(Don't use the line number and colon sign on the
program.)
1.
List out the major components of the C program?
2.
Draw a figure of the compilation process in C programming.
Header Files
and C Preprocessor
Header Files are standard files of C-programming language.
It contains the function definition of library functions. They are written at
the top of the program. Some header files are given below.
POINTS TO REMEMBER
|
|
Header files are compulsory in language. That
contains the function definition of library functions. |
●
#include<stdio.h>: It is a standard input output
header file. It contains the function definition of input output functions such
as scanf(), printf() etc.
●
#include<conio.h>: It is a header file which is
included in the program. This is used for
clrscr(), getch(), etc. We do not need to include this file in the C
program. It is necessary for C++ programs. conio stands for CONsole Input
Output header file. The clrscr() helps to clear the screen.
●
#include<math.h>: This header file is used for
mathematical functions such as pow(), sqrt(), sin(), tan() , cos() etc.
●
#include<string.h> :It is string header file. It
contains the function definition of string processing functions such as
strlen(), strcat(), strcpy() etc.
C
Preprocessor
Preprocessor is a program that processes the code before it
passes through the compiler. It operates under the control of preprocessor
command lines and directives. Preprocessor directives are placed in the source
program before the main line, before the source code passes through the
compiler. It is examined by the preprocessor for any preprocessor directives.
If any appropriate actions are taken then the source program is handed over to
the compiler.
POINTS
TO REMEMBER
Preprocessor is a program that processes the code before it
passes through the compiler. It operates under the control of preprocessor command
lines and directives.
Preprocessor directives follow the special syntax rules and
begin with the symbol # and do not require any semicolon at the end. A set of
commonly used preprocessor directives are:
|
Directive |
Function |
|
#define |
Defines a macro substitution and symbolic constant |
|
#include |
Specifies a file to be included in the program |
Keywords
●
C language: C language has been designed and
developed by Dennis Ritchie at Bell Laboratories in 1972.
●
Features of C language: C language is portable, procedural,
general purpose, structured, standardized and compact programming Language.
●
Disadvantages of C language: Some disadvantages of C language
are no runtime checking, no strict type checking. It may be compile time
overhead due to the misplacing and excessive use of pointers.
●
Components of C: The main components of C are
Comments, header files, function header, global declaration, main(),
Declaration part, Executable part and user defined functions
●
Header files: Header files are standard files
that are compulsory in C program and contains the function definition of
library functions
●
Preprocessor: Preprocessor is a program that
processes the code before it passes through the compiler. It operates under the
control of preprocessor command lines and directives.
2.
Explain compilation process with appropriate block diagram.
3.
Why are header files needed in every C program? Explain.
4.
Write down the importance of the header file and explain
briefly about any three header files of
C language.
5.
What is a pre-processor? List any two preprocessors.
