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4.
C Programming
Structured
programming
Advantages
of structured programming
a)
Reduces complexity and easy to code.
b)
It takes less time to program and
easy to debug.
c)
Reuse of modules and flow of control
is clear.
C language
C
Language is a high-level structured programming language which is used to
develop system software.
Dennis Ritchie at Bell telephone laboratory developed
C-language in early 1970s.
C is called middle level language because it combines
elements of high level language with some features of assembler.
Data types used in
C
Data
type are means to identify the type data and associated operation of handling
it.
Data types used in C language
a) char b)
int c)
float d)
double e)
void
Why C is called a middle level
language?
C is called middle level language
because it combines elements of high level language with some features of
assembler
Features of C language
· Portability: C
code can be compiled and executed on different systems with minimal
modifications.
· C combines
elements of a high level language with some features of assembler which helps
to manipulates memory address.
· C is a
case-sensitive programming language. It understands the capital alphabets and
small alphabets as different values.
· C is many time
faster and efficient than BASIC due to the variety of data type and a list of
powerful operators, programs written in C language.
Limitations
of C language
a)
There is no runtime checking. It has
poor errors detection system.
b)
It
does not support object oriented programming.
c)
C
language has only 32 Keywords
d)
There is no strict type checking int
data type to float variables.
Application of C Language
a) Operating System
b) Language Compilers/Interface
c) Assemblers
d) Text Editors
e) DBMS
f) Utilities etc.
C Token
C tokens are the basic buildings blocks in C language
which are constructed together to write a C program.
Each and every smallest individual unit in a C program
are known as C tokens
C tokens are of six types.
a) Keywords (eg: int, while),
b) Identifiers (eg: main, total),
c) Constants (eg: 10, 20),
d) Strings (eg: “total”, “hello”),
e) Special symbols (eg: (), {}),
f) Operators (eg: +, /,-,*)
C keywords (reserved word)
Keyword is a set of special words which are already
defined for some tasks.
C has only a set of 32 keywords, which have their
predefined meaning and cannot be used as a variable name.
E.g. auto,
double, int struct, break, else, long, switch, case, enum, register, typedef,
char, extern, return, union, continue, for, signed, void, do, if, static,
while, default, goto, sizeof, volatile, const, float, short, unsigned
C Character set
Character Set is a group of valid characters and
symbols supported by a programming language. Alphabets, Digits and Special
characters.
Identifiers
Identifiers are the names given to the entities such
as variables, functions, arrays structures and unions.
E.g. int price; float total; Here, price and total are
called identifiers.
Rules for naming Identifiers:
i) The Identifier must start with an alphabet or an
under score (_).
ii) Identifier can be made from the combination of
alphabets, digits and under score.
iii) No any C keyword can be used as an Identifier.
iv) Identifier must be unique and can be used for a
single purpose only.
Format Specifier
The format specifier is used during input and output
operation. It tells the compiler what type of data is stored in a variable
during the input and output operation such as taking data from keyboard and
display data on the screen. Some examples are %c, %d, %f, etc.
|
Data Type |
Format Specifier |
|
short int |
%hd |
|
unsigned short int |
%hu |
|
unsigned int |
%u |
|
int |
%d |
|
long int |
%ld |
|
unsigned long int |
%lu |
|
char |
%c |
|
float |
%f |
|
double |
%lf |
C Header Files
stdio.h - Used for standard input and output (I/O)
operations. [printf( ), scanf( ), getchar( )]
conio.h -
Contains declaration for console I/O functions. [clrscr( ), exit( )]
math.h - D e c l a r e s m a t h e m a t i c a l
functions and macros. [pow(), squr(), cos(), tan(), sin(), log() ]
string.h - Used for manipulating strings. [strlen(),
strcpy(), strcmp(), strcat(), strlwr(), strupr(), strrev() ]
Escape Sequence
Escape Sequence is a pair of character that is used
with printf() function to display non-printing character or a special character
on the screen.
Some Examples of Escape Sequence:
\n - new line
\t - tab
\b - backspace
\o - null character
\? - question mark
\\ - slash
\' - single quote
\” - double quote
Format Identifier
We need to include format identifier to tell the data
type in the area of format string of printf() function.
|
Variable Type |
Format Identifier |
|
char |
%c |
|
int |
%d |
|
long int |
%ld |
|
float |
%f |
Variable
A variable is a location in the memory of a computer
which holds data in a program and its value may change during the execution of
program.
Constant
Constant are the values that do not change
during the execution of a program.
String Constant
String constant
is a message to be displayed along with the other values stored in variables.
It is enclosed within double quotation (" ").
Output Function in C
Output function is used to show the calculated result
or output on the screen.
In C language, printf() is one of the output function
defined in header file.
printf() function
In C Language, printf() function is used to print the
valued on the screen.
It is defined in header file. So, the header file must
be added to use this function.
Input Function in C
Input function
is used to ask data for processing.
In C language, scanf() is one of the input function
defined in header file.
scanf() Function
scanf() is one of the most important functions of C
Program.
This function is also defined in the header file and
used to ask value from keyboard.
getch() function
getch() function is another input function of C
language.
This function is defined in the header file .
This function is used to ask any one character from
keyboard.
Arithmetic Calculations in C Program
There are basically four types of arithmetic
operations:
i) Addition
ii) Subtraction
iii) Multiply
iv) Division
List of Arithmetic Operators in C
+ (Plus) - Addition
- (Minus) – Subtraction
* (Asterisk) – Multiplication
/ (Slash) – Division
% (Percentage Symbol) – Modulus Division
++ (Plus Plus) – Increment Operator
- - ( M i n u s M i n u s ) – Decrement Operator
Operator
Operators are
special symbols that are meant for specific tasks or operators.
The different
types of C operators are:- Arithmetic operators, Assignment operators, Unary
operators, Relational operators, Logical
operators and Conditional operators.
Arithmetic
operators are the operators that are used for manipulating arithmetic data and
performs arithmetic operation. The arithmetic operators are:- +,
- , * , / and
%
The operator that
operate on one operand variable or constant is called urinary operator. E.g.
++, - -
C Expression
An expression consists of at least one operand with
one or more operators. It is a legal combination of symbols that represents a
value.
Logical Calculation in C
The calculation that is done based on one or more
conditions is called logical calculations.
Several relational or comparison operators are used to
check the condition which gives True or False as a calculated result.
Relational Operators in C
Relational Operator checks the relationship between
two operands and returns either 1 (True) or 0 (False).
In C programming, relational operators can be used to
take decisions and provide condition in looping statements.
List of Relational Operators in C
= = Equal to
> Greater than
< Less than
!= Not equal to
>= Greater than or equal to
<= Less than or equal to
Control structures in C
a) Sequence structure (straight line
paths)
The statements are executed one after another
sequentially from top to bottom without changing the flow of program.
b) Selection structure (one or many
branches)
The control of the program is transferred from one
part of the program to another on the basis of specified condition or without
condition.
If statement and switch statement are the examples of
selection structure.
c) Loop structure (repetition of a set of
activities)
Looping is the process of repeating the execution of a
statement or a block of statements guided by a condition. A loop is terminated
when the given condition is satisfied.
Looping statements in C
C provides three kinds of loops: i) while loop ii) do
loop iii) for loop
Give the name of any two header
files used in C language
<stdio.h> and <conio.h>
Name the header/library file that
handles mathematical functions in C Language. - <math.h>
What will be the value of ‘y’ in
given C expression, y=64%5?
The value of y will be 4.
What will be the value of x in given c
expression x=55 % 10?
The
value value of x will be 5.
How many keywords are in C language?
- 32
What is an operator in C language?
Operator is a symbol that is used to
perform mathematical operations.
Write the name of unary operators used in
C-language
Increment
(++) and decrement (--).
Write the name of two selection
statement used in C language.
- if and switch statement
Write any two looping statements
used in C language.
for and while loop
List any two examples of format
specifier (Conversion Character) used in C Language. - %d
(int) and %f (float)
Write
down the backslash character (Escape sequence) for horizontal tab and new line
in C program
The
backslash escape sequences for horizontal tab is \t and for new line is \n in C
program.
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