Data types, operators and control structures unit-2.pdf

UNIT-2
DATA TYPES, OPERATORS, AND
CONTROL STRUCTURES
FACULTY NAME: Er. Kamaldeep Kaur

CHAPTER CONTENTS
 BASIC DATA TYPES, DERIVED DATA TYPES,
 KEYWORDS, IDENTIFIERS, CONSTANTS AND VARIABLES,
 TYPE CASTING,
 OPERATORS, AND OPERATOR PRECEDENCE.
 CONTROL STRUCTURES: IF STATEMENT, SWITCH-CASE, FOR,
WHILE AND DO-WHILE LOOPS, BREAK AND CONTINUE
STATEMENT

INTRODUCTION
 C++ was developed by Bjarne Stroustrup, in
early 1980s.
 C++ is an extension of C with a major addition
of the class construct feature.
 Stroustrup initially called the new language as
‘C with classes’.
 The name was later changed to C++, from the
increment operator ++, suggesting that C++ is
an incremented version of C.

C++ BASIC ELEMENTS
 Programming language is a set of rules, symbols,
and special words used to construct programs.
 Character Set: a set of valid characters that a
language can recognize.
 Letters: A-Z, a-z
 Digits: 0-9
 Special Characters
Space + * / ^ () [] {} = != <> ‘ “ $ , ; : % ! & ?
_ # <= >= @
 Formatting characters backspace, horizontal tab, vertical tab,
and carriage return

TOKENS
 Tokens are the basic building blocks in C++
language.
 The smallest individual units in a program are known
as tokens.
 A program is constructed using a combination of
these tokens.

TYPES OF TOKENS
 KEYWORDS
 IDENTIFIERS
 CONSTANTS
 STRING
 SPECIAL SYMBOLS (PUNCTUATORS)
 OPERATORS

KEYWORDS
 Explicitly reserved identifiers
 Cannot be used as names for the program variables
or other user-defined program elements
 There are 32 keywords, that were present in C
language and have been carried over into C++ :
 auto const double float int short struct
unsigned break continue else for long signed
switch void case default enum goto register
sizeof typedef volatile char do extern if return
static union while

KEYWORDS
 There are another 30 reserved words that were not
in C, are therefore new to C++, and here they are:
 asm dynamic_cast namespace
reinterpret_cast try bool explicit new
static_cast typeid catch false operator template
typename class friend private this using const_cast
inline public throw virtual delete mutable protected
true wchar_t

IDENTIFIERS
 Identifiers refers to the name of variables,
functions, arrays, classes, etc. created by the user.
Identifiers are the fundamental requirement of any
language.
 Identifier naming conventions
 Only alphabetic characters, digits and underscores are
permitted.
 First letter must be an alphabet or underscore (_).
 Identifiers are case sensitive.
 Reserved keywords can not be used as an identifier's name.

IDENTIFIERS
IDENTIFIER NAME VALID OR INVALID
5th_element Invalid (begins with a digit)
_delete Valid
School.fee Invalid (dot not allowed)
register[5] Invalid (keyword)
Student[10] Valid
Employee name Invalid (white space)
Perimeter() Valid

IDENTIFIERS
 A major difference between C and C++ is the limit
on the length of a name.
 C recognizes only the first 32 characters in a name
 C++ places no limit on its length, and, therefore, all
the characters in a name are significant.

CONSTANTS
 Refer to fixed values that do not change during the
execution of a program.
 Also known as literals.
 Types of literals in C++:
 Integer constant
 Character constant
 Floating (real) constant
 String constant

CONSTANTS
 EXAMPLES
 123 //integer constant
 12.34 //floating point constant
 ‘A’ //character constant
 “C++” //string constant

 ** void is used:
 To specify the return type of a function when it is
not returning any value
 To indicate an empty argument list to a function.

STRING
 used to store letters and digits.
 referred to as an array of characters as well as an individual
data type.
 enclosed within double quotes, unlike characters which are
stored within single quotes.
 The termination of a string in C++ is represented by the null
character, that is, ‘0’
 Examples:
 char name[30] = ‘’Hello!”;
 char name[] = “Hello!”;
 char name[30] = { ‘H’ , ’e’ , ’l’ , ’l’ , ’o’};;
 string name = “Hello”

SPECIAL SYMBOLS (PUNCTUATORS)
Special
Character
Name Function
[ ]
Square
brackets
The opening and closing brackets of an array symbolize
single and multidimensional subscripts.
()
Simple
brackets
The opening and closing brackets represent function
declaration and calls, used in print statements.
{ } Curly braces
The opening and closing curly brackets to denote the start
and end of a particular fragment of code which may be
functions, loops or conditional statements
, Comma
We use commas to separate more than one statements, like
in the declaration of different variable names
#
Hash / Pound /
Preprocessor
The hash symbol represents a preprocessor directive used
for denoting the use of a header file
* Asterisk
We use the asterisk symbol in various respects such as to
declare pointers, used as an operand for multiplication
~ Tilde We use the tilde symbol as a destructor to free memory
. Period / dot The use the dot operator to access a member of a structure

OPERATORS
 Operators are tools or symbols which are used to
perform a specific operation on data.
 Operations are performed on operands.
 Operators can be classified into three broad
categories according to the number of operands
used:
 Unary operators
 Binary operators
 Ternary operators

UNARY OPERATORS
 The operators that operate a single operand to
form an expression are known as unary operators.
 Examples:
 + + (increment) operator,
 -- (decrement) operator,
 unary minus operator.

BINARY OPERATORS
 The operators that operate on two or more
operands are known as binary operators.
 Examples:
 Arithmetic Operators
 Assignment Operator
 Relational Operators
 Logical Operators
 E.g. a+b, a-b, a*b, a/b etc.

TERNARY OPERATORS
 The operator that operates minimum or maximum
three operands is known as ternary operator.
 There is only one ternary operator available in
C++.
 The operator ?: is the only available ternary
operator i.e. used as a substitute of if-else
statement.• E.g. a>b ? a:b

OPERATORS BASED ON TYPE OF OPERATION
 Arithmetic Operators
 Assignment Operators
 Relational Operators
 Logical Operators
 Increment Decrement Operators
 Conditional Operator

ARITHMETIC OPERATORS
 An operator that performs an arithmetic operation
is known as arithmetic operator
 It is a binary operator

RELATIONAL OPERATORS
 An operator that is used to test the relation between
two values or operands.
 Relational Operators are BINARY operators.
 These operators evaluate to true or false.
 Return zero for false and a non zero for true.
 Also known as Comparison operators.

LOGICAL OPERATORS
 The operators that are used to combine the result of
one or more relation.
 These operators evaluate to true or false.
 Are Unary and Binary Operators.

INCREMENT & DECREMENT OPERATORS
 ++ Increments value by 1
 x++ / ++x Equivalent to X=X+1
 -- Decrement value by 1
 x-- / --x Equivalent to X=X-1
 ++x and --y are called prefix operator, that means the increment or
decrement operators modify their operand before it is used or assigned.
 Example a = 10; b = ++a; a is incremented by 1 and then assign to b.
Therefore both a and b have the value of 11.
 x++ and y-- are called postfix operator, the increment or decrement
operators modify their operand after it is used. a = 10; b = a++; value of
a is assigned to b then a is incremented by 1. Therefore here a=11 and
b=10.

INCREMENT & DECREMENT OPERATORS

OPERATOR PRECEDENCE & ASSOCIATIVITY
 Operator precedence determines the grouping of
terms in an expression.
 The associativity of an operator is a property that
determines how operators of the same precedence
are grouped in the absence of parentheses. This
affects how an expression is evaluated.

Data types, operators and control structures unit-2.pdf

TYPE CONVERSION
 It is the process of converting one data type to
another i.e. converting an expression of given type
into another
 Two types:
 Implicit (automatic)
 Explicit (type casting)

AUTOMATIC TYPE CONVERSION
 It is automatically performed when:
1. Constants and variables of different types are mixed in an
expression
 For a binary operator, if the operands type differ, the
compiler converts one of them to match with the other, using
the rule that smaller type is converted to the wider type.
 For example, if one of the operand is int and other is float,
then int is converted to float because a float is wider than int.
 For example, m = 5 + 2.75
 ‘5’ would be converted to float as 5.00

AUTOMATIC TYPE CONVERSION
2. An assignment operator also causes automatic type conversion.
 The type of data to the right of an assignment operator is
automatically converted to the type of the variable on the left.
 For example, int m;
float x=3.14459;
m=x;
 The fractional part is truncated.
 The type conversions are automatic with built in data types.

TYPE CASTING
 The explicit type conversion is done using type cast operator.
 Syntax: datatype(expression)
 datatype is the type which we want the expression to get
changed as
 For example,
int a;
float b,c;
cin>>a>>b;
c= float(a)+b;
cout<<c;
 O/P: 10 //a
12.5 //b
22.5 //c

CONTROL STRUCTURES
 Programs are written using four basic structures
 Sequence: a sequence is a series of statements that execute
one after another
 Selection(branching): selection (branch) is used to execute
different statements depending on certain conditions
 Repetition(loop or iteration): repetition (looping) is used to
repeat statements while certain conditions are met
 Jumping: jump from one point of program to another
 Called control structures or logic structures

SEQUENCE CONTROL STRUCTURE
 The sequence structure directs the computer to
process the program instructions, one after another,
in the order listed in the program.

SELECTION CONTROL STRUCTURE (BRANCHING)
 makes a decision and then takes an appropriate
action based on that decision
 Also called the decision structure

SELECTION (BRANCHING OR CONDITIONAL)
 If
 if-else
 nested if (if- elseif- elseif- else)
 switch

Simple If STATEMENT
 if(condition)statement
 If the condition is true, statement is executed.
 If the condition is false, statement is not executed.
 EXAMPLE:
if (x==100)
cout<<“x is 100”;

If else STATEMENT
 if (condition)statement1
else statement2
 If condition is true, statement1 is executed and if the
condition is false, statement2 is executed
 EXAMPLE:
if (x==100)
cout<<“x is 100”;
else
cout<<“x is not 100”;

Nested if STATEMENT
 When if statement occurs with in another if
statement, then such type of if statement is called
nested if statement.
 if (condition1)
if (condition2)
statement-1;
else
statement-2;
else
statement-3;

Nested if STATEMENT
 EXAMPLE:
if(a>=b && a>=c)
cout<<“a is biggest”;
elseif(b>=a &&b>=c)
cout<<“b is biggest”;
else
cout<<“c is biggest”;

Switch STATEMENT
 EXAMPLE:
int main(){
int a; cin>>a;
switch(a) {
case 1: cout<<“the value is 1”; break;
default: cout<<“out of range”;
}
return 0;
}

DIFFERENCE BETWEEN SWITCH & IF-ELSE

REPETITION (LOOP OR ITERATION)
 directs computer to repeat one or more instructions
until some condition is met
 Also called a loop or iteration

REPETITION (LOOP OR ITERATION)
 While
 do-while
 For
 Nesting

LOOPS (ITERATION)
 Loops have an objective to repeat a certain number
of times or while a condition is fulfilled. When a
single statement or a group of statements will be
executed again and again in the program then such
type of processing is called loop. Loop is divided
into two parts
 Body of loop
 Control of loop

CONTROL OF LOOP
 Control of loop is divided into two parts:
 Entry control loop- in this first of all condition is
checked if it is true then body of the loop is executed.
Otherwise we can exit from the loop when the
condition becomes false. Entry control loop is also
called base loop. Example- While loop and for loop
 Exit control loop- in this first body is executed and
then condition is checked. If condition is true, then
again body of loop is executed. If condition is false,
then control will move out from the loop. Exit control
loop is also called Derived loop. Example- Do-while

LOOP STATEMENTS
 The loop statements in C++ language are-
 While loop
 Do loop/Do-while loop
 For loop
 Nested for loop

WHILE LOOP EXAMPLE
 #include<iostream.h>
int main()
{
int n;
cout<<“Enter the starting number”;
cin>>n;
while(n>0){
cout<<n<<“,”;
n--;
}
cout << “FIRE!“;
return 0;
}

WHILE VS DO WHILE
ENTRY CONTROLLED EXIT CONTROLLED

FOR LOOP
 For loop is an Entry control loop when action is to
be repeated for a predetermined number of times.
 Four parts
 Initialise expression
 Test expression (condition)
 Body (loop statements)
 Increment/ decrement (modification)

NESTING OF FOR LOOPS
 A loop can be inside another loop.
 C++ can have 256 levels of nesting.
 for(init;condition;increment)
{
for(init;condition;increment)
}
statement(s);
}
statement(s);
}

JUMPING STATEMENTS
 Jump statements are used to alter the flow of
control unconditionally.
 That is, jump statements transfer the program
control within a function unconditionally.
 The jump statements defined in C++ are break,
continue, goto.

Goto STATEMENT
 It allows making an absolute jump to another point
in the program.

Goto STATEMENT
 #include<iostream.h>
int main()
{
int n=10;
loop:
cout<<n<<“,”;
n--;
if(n>0) goto loop;
return 0;
}

BREAK STATEMENT
 Goes straight to the end of a do, while or for loop or a switch
statement block.
 EXAMPLE:
#include<iostream.h>
int main(){
int n;
for(n=10;n>0;n--){
cout<<n<<“,”;
if(n==5){
cout<<“count down aborted!”;
break;}}
return 0;}
O/P: 10,9,8,7,6,5,count down aborted!

CONTINUE STATEMENT
 Goes straight back to the start of a do, while or for loop
 EXAMPLE:
#include<iostream.h>
int main(){
int n;
for(n=10;n>0;n--){
if(n==5)continue;
cout<<n<<“,”;}
return 0;}
O/P: 10,9,8,7,6,4,3,2,1,FIRE!

Data types, operators and control structures unit-2.pdf

Recommended

More Related Content

Similar to Data types, operators and control structures unit-2.pdf (20)

More from gurpreetk8199 (7)

Recently uploaded (20)

Data types, operators and control structures unit-2.pdf