LET’S LEARN
INTRODUCTION
TYPES OF OPERATORS
1. Arithmetic Operators
2. Unary Operators
Increment operator (++)
Decrement operator (- -)
Unary Plus Operator (+)
Unary Minus Operator (-)
sizeof() Operator
Explicit Type Casting Operator
Bitwise Complement Operator (~)
3. Assignment Operator
4. Compound Assignment Operators
5. Relational (Comparison) and Equality Operators
6. Logical Operators
&& (AND) Operator
|| (OR) Operator
! (NOT) Operator
7. Conditional Operator ( ? : )
8. Comma Operator
9. Scope Resolution Operator
10. Address & Pointer Operators
11. Bitwise Operators
OPERATOR PRECEDENCE
CHAPTER EVALUATION EXERCISE
INTRODUCTION TO OPERATORS
Operators are characters or signs that represent
mathematical or logical operations. Eg: + - / % > =
To
calculate the final result, operators use one or more values called operands. Operands are data
values or data holders (variables) that can be operated upon or manipulated by
an operator. Eg: 14, 24 are operands in the expression 14+24
Operators and
Operands work together to form an expression. Expression is a sequence of operands
and operators that specifies a computation. Eg : a=42, 2+2
, a=b+c, a<b etc are expressions.
y
+ 12 = 28
|
|
Expression
|
y + 12 = 28
|
Operators
|
+ =
|
Operands
|
12, 28, y
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Variable
|
y
|
Operators in C++ are broadly classified into 3 "categories":
Unary Operator - work with one operand
Binary Operator - work with two operand’s
Ternary Operators - conditional operators that work with 3 operand’s
Operators
in C++ can be of 10 different "types". Let’s quickly discuss each one of
them.
1. Arithmetic Operators
Arithmetic Operators are binary operators that support arithmetic operations. The five
arithmetic operations supported by C++ language include: addition(+), subtraction(-), multiplication(*),
division(/), and Modulo (%).
The first 4 corresponds
to their respective mathematical operators. The Modulo/Mod operator is used to
find remainder of the division between two values. For example, in the expression a
= 11%3, variable a will
contain value 2, since the remainder after dividing 11 by 3 is 2.
2. Unary Operators
Unary Operators work with one operand and includes ++, --, + (unary plus), - (unary minus), ~ (bitwise complement), ! (not), sizeof() and Typecast.
Note : “!” or the Logical NOT Operator is discussed under Logical Operators.
Unary Operators work with one operand and includes ++, --, + (unary plus), - (unary minus), ~ (bitwise complement), ! (not), sizeof() and Typecast.
Note : “!” or the Logical NOT Operator is discussed under Logical Operators.
Increment operator (++) is a unary operator that increases the value
stored in a variable by 1. This is equivalent to +1. Increment operators can be pre-increment (++a) or post-increment
(a++).
- A pre-increment operator (prefix) is used when the value within an expression is to be incremented first, and then assigned to an operand. For example:
If a=5, then b=++a would result in a=6, b=6
- A post-increment operator (suffix) is used when the value within an expression is to be assigned to an operand first, and then incremented. For example:
If a=5, then b=a++ would result in a=6, b=5
Decrement operator (- -) is a unary operator that decreases the value
stored in a variable by 1. This is equivalent to -1. Decrement operators can be pre-decrement (- -a) or post-decrement
(a - -).
- A pre-decrement operator (prefix) is used when the value within an expression is to be decremented first, and then assigned to an operand. For example:
If a=5, then b = - -a would result in a=4, b=4
- A post-decrement operator (suffix) is used when the value within an expression is to be assigned to an operand first, and then decremented. For example:
If a=5, then b = a-- would result in a=4, b=5
Unary Plus Operator (+) assigns positive value to an operand of any
numeric type. This operator has been preset as default for all numeric types. Eg: +3
Unary Minus Operator (-) negates or assigns negative value to an operand of type integer,
floating-point or decimal. Eg: -3
sizeof() Operator is a unary operator that returns
the size of a data type or variable in Bytes. It accepts one parameter,
which is either a data type or a variable.
Example: b = sizeof (char) ;
Explicit
Type Casting Operator is a unary operator that allows to convert one data type into another data type. There are several ways to do this in C++.
The simplest one, which has been inherited from the C language, is to precede
the expression to be converted by the "new data type" enclosed between parentheses.
int i ;
float f = 3.14 ;
i = (int)f ;
In the above example, float number 3.14 is converted to an integer value 3, after typecasting. Here, the typecasting operator was (int). Another way to do the same thing in C++ is using the typecast expression: i = int(f) ;
In the above example, float number 3.14 is converted to an integer value 3, after typecasting. Here, the typecasting operator was (int). Another way to do the same thing in C++ is using the typecast expression: i = int(f) ;
Bitwise Complement Operator (~) also called the One’s Complement Operator, is a unary operator that is used with numeric operand types for inverting each bits of its binary representation (0 to 1 and 1 to 0). The result of the operation is a bitwise complement (inverse of the binary representation) of the operand. For example:
Decimal
|
Binary
|
Bitwise Complement (~)
|
3
|
0000 0011
|
~ 3 = 1111 1100
|
3.
Assignment Operator
The assignment operator (=) is a binary operator that assigns a value on Right Hand Side (RHS) to a variable on the Left Hand Side (LHS).
The assignment operator (=) is a binary operator that assigns a value on Right Hand Side (RHS) to a variable on the Left Hand Side (LHS).
Example: a = 5 ;
Here, an integer value 5 is put into memory location (variable) named a. The LHS part of assignment operator (=) is known as the lvalue (left value) and the RHS part is known as the rvalue (right value). The lvalue has to be a variable whereas the rvalue can be a constant, a variable, the result of an operation or any combination of these. The most important rule when assigning is the right-to-left rule. The assignment operation always takes place from right to left, and never the other way. For example lets consider: a = b ;
This expression assigns the value contained in variable b (the rvalue) to variable a (the lvalue). If a had some previous value, it gets lost.
PROGRAM 7: Declare 2 variables a, b with values 10, 4 respectively. Assign b to a. Change b to 7. Print final values of a, b.
Here, an integer value 5 is put into memory location (variable) named a. The LHS part of assignment operator (=) is known as the lvalue (left value) and the RHS part is known as the rvalue (right value). The lvalue has to be a variable whereas the rvalue can be a constant, a variable, the result of an operation or any combination of these. The most important rule when assigning is the right-to-left rule. The assignment operation always takes place from right to left, and never the other way. For example lets consider: a = b ;
This expression assigns the value contained in variable b (the rvalue) to variable a (the lvalue). If a had some previous value, it gets lost.
PROGRAM 7: Declare 2 variables a, b with values 10, 4 respectively. Assign b to a. Change b to 7. Print final values of a, b.
#include <iostream>
int main ()
{
int a, b;
a = 10; b = 4;
a = b; b = 7;
std::cout << "a:";
std::cout << a;
std::cout<<
"\n";
std::cout <<
"b:";
std::cout << b;
}
|
Output
a:4
b:7 |
A property that C++ had started over
other programming languages is that the assignment operation can be used as the
rvalue (or part of the rvalue) for another assignment operation. For example:
p = 3 + (q = 9) ;
is equivalent to:
q = 9 ;
p = 3 + q ;
This means, first assign 9 to variable q, then compute 3 + 9 and then put the result 12 into variable p.
The following chain expression is also valid in C++:
a = b = c = 14 ;
It assigns 14 to all the three variables a, b and c.
a = b = c = 14 ;
It assigns 14 to all the three variables a, b and c.
4. Compound
Assignment Operators
Compound Assignment Operators are binary operators that are used for quick coding purposes on variables with existing values. It includes the following operators: +=, -=, *=, /=, %=, >>=, <<=, &=, ^=, |=
Compound Assignment Operators are binary operators that are used for quick coding purposes on variables with existing values. It includes the following operators: +=, -=, *=, /=, %=, >>=, <<=, &=, ^=, |=
For example, if m=2, n=3 then m+=n means:
m = m+n or m = 2+3
Final values of m and n become:
m = 5, n = 3
m = 5, n = 3
#include <iostream>
int main()
{
int a,b,c;
a=b=c=5;
c*=((a+=3)-(b/=2));
std::cout
<< "a=" << a;
std::cout
<< "\nb=" << b;
std::cout
<< "\nc="<<c;
}
|
Output
a=8 b=2 c=30 |
5.
Relational (Comparison) and Equality Operators
Relational and Equality operators are binary operators that are used to
compare and check two expressions. The result is a Boolean value (true or false, 1 or 0). Relational and Equality
operators include: <,
>, <=, >=, = =, !=, <=>
Here are some examples:
Instead of using only numeric constants, we can also
use any valid expression, including variables. Suppose that a=2, b=3 and c=6, then
= operator is an assignment operator. It assigns
the value on its right side to the variable at its left side. Eg: p = 8;
== operator is the equality operator. It compares whether operands or expressions
on both sides of it are equal to each other. Eg: 5==5 returns true.
In the expression (b=2)
== a, we first assigned the value 2 to b and then compared it to a
(which already has value 2). The final result is true.
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Note: The 3-way comparison operator also called the spaceship operator and represented by <=>, takes two values a, b and determines if a<b,
a=b, or a>b in a single operation. It is a new inclusion in C++20 and
is used in preprocessor based instruction sets (part of machine language coding).
6.
Logical Operators
Logical (boolean) operators are used to check conditions between operands or expressions. Logical operators can be unary or binary. There are 3 Logical operators: && (AND), || (OR), ! (NOT ). It
responds to the computer as a TRUE or FALSE value. In C++, TRUE value is
represented by 1 and FALSE value by 0.
Eg: if AGE >=18 && AGE<=25 then print NAME
(the statement prints candidate names between age group
18 and 25)
&& (AND) Operator
The && operator is a binary operator that checks conditions
where both the operands (or expressions) have to be satisfied. If both the conditions are TRUE,
1 is returned otherwise 0 is returned. If any one condition goes wrong (FALSE),
then final result will be FALSE. The following list shows result of && Operator for 2 conditions
(operands) a and b. If both a,
b are TRUE, then a && b is TRUE, else all other
conditions are FALSE.
Note: AND operator functions like multiplication.
False AND False = False
0 * 0 = 0
True AND True = True
1 * 1 = 1
False AND True = True
0 * 1 = 0
True AND False = True
1 * 0 = 0
|| (OR) Operator
|| operator is a binary operator that checks conditions
where any one of the operands/expressions
have to be satisfied. If any one condition is TRUE, 1 is returned otherwise 0
is returned. The following list shows result of || operator for 2 conditions (operands) a and b. If either a, b
are TRUE, then a || b is TRUE, else the
condition is FALSE.
Note: OR operator functions like addition.
False OR False = False
0 + 0 = 0
True OR True = True
1 + 1 = 2 (or >0)
False OR True = True
0 + 1 = 1
True OR False = True
1 + 0 = 1
Check these expressions:
! (NOT) Operator
!
operator is
a unary operator that checks for one
condition that is located to its right and then inverts the value. If condition
is satisfied (TRUE), it gives FALSE value and if condition is not satisfied (FALSE),
it gives TRUE value. For example:
7.
Conditional Operator
The conditional operator is a ternary operator that evaluates an
expression having one condition and 2 possible results. If the result is TRUE,
then result 1 is executed otherwise result 2 is executed. It is used with a
combination of 2 operators namely ?
and :
Syntax for using a conditional operator is:
condition ? result1 :
result2
PROGRAM 9:Print the biggest among 2 numbers using conditional operator.
#include <iostream>
int main ()
{
int a,b,c;
std::cout<< "Enter first number:
";
std::cin>>a;
std::cout<< "Enter second number:
";
std::cin>>b;
c = (a>b) ? a : b;
std::cout << "Biggest number is:
"<<c;
}
|
Output
Enter first number: 28
Enter second number: 24 Biggest number is: 28 |
8.
Comma Operator
We have seen how comma (,) has been used as a
separator ( eg: int a, b; ). Comma can also
be used as an operator. Comma operator
is a binary operator that is used to join together 2 or more expressions whose
operations will be executed in a sequence. In the following code:
j=(k=3, k+=2);
3 is first assigned to k,
next the value of k is incremented by 2,
then value of the final expression on RHS is assigned to LHS.
So finally, variable ‘j’ would contain the value 5 while variable
‘k’ would also contain value 5.
PROGRAM 10:
Using comma operator, assign b=5, then use compound assignment b*= 4. Assign the
above 2 comma operated expressions to a. Print values of a, b.
Again, using
comma operator assign b=5, then compute b*4, assign c=12. Assign the above 3 comma
operated expressions to a. Print values of a,b,c.
Check the difference between working of above two expressions.
#include <iostream>
int main()
{
int a, b, c;
a=(b=5, b*=4);
std::cout << "a=" <<
a<<"\nb="<<b;
a=(b=5, b*4, c=12);
std::cout << "\na=" <<
a<<"\nb="<<b<<"\nc="<<c;
}
|
Output
a = 20
b = 20
a = 12
b = 5
c = 12
|
9. Scope Resolution Operator
The scope resolution
operator, represented by :: is both a
unary and binary operator. It is used to extend
the accessibility and override the
characteristics of variables, functions,
class and objects stored globally
for use in local area of a program.
Eg: std::cout<<”Hello”;
PROGRAM 11: Declare an integer variable n as local & global variable with different values. Print both the values of n.
|
#include
<iostream> int n = 15; int main () {
int n = 9;
std::cout<<”Local
value of n = ”<<n<<”\n”;
std::cout<<”Global value of n = ”<<:: n; }
|
Output
Local value of n = 9
Global value of n = 15
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10. Address & Pointer Operators
& operator or address operator
is a unary operator.
It is also called the "Address of" operator. It points to the address of a variable.
* operator or pointer operator is a
unary operator. It is also called the "Value at" operator or the "Indirection" operator. It points
to the value stored within a particular memory address.
For example :
&n
|
gives address of the memory location whose name is ‘n’
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* (&n)
|
gives value stored within memory address specified by &n
|
PROGRAM 12: Declare “i” as integer variable and “p”
as pointer to integer. Assign value 20 to i. Print the value of “i” normally and by pointer operator.
Also print address location of variable “i”
by address operator and pointer.
|
#include
<iostream> int
main () { int
i, *p; // declare i and
pointer p of data type integer p=&i; // assign memory address of i to pointer p i=20;
std::cout<<"Normally
i = "<< i <<"\n"; std::cout<<"By
pointer operator i = "<< *p <<"\n"; std::cout<<"Memory
location of i by address operator = "<< &i
<<"\n"; std::cout
<<"Memory location of i by pointer = "<< p
<<"\n"; }
|
Output
Normally i = 20
By pointer operator i = 20
Memory location of i by address operator = 0x6ffe04
Memory location of i by pointer = 0x6ffe04
|
11. Bitwise Operators
A
bitwise operator processes each bit of the binary value of an operand. There are 6 bitwise
operators: AND (&), OR (|), NOT(~), XOR (^),
Right Shift (>>), Left Shift (<<).
In the byte format (8-bit), the
decimal number 1 is represented as a string of binary digits 0000 0001
while number 5 is represented as the string 0000 0101. Bitwise operators
act on each bit within the string of binary digits representing a number.
Refer to the
table below, where p = 10 (0000 1010 in binary) and q = 4 (0000
0100 in binary).
Operator
|
Meaning
|
Example
|
Explanation of example
p = 10 (0000 1010)
q = 4 (0000
0100)
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&
(Bitwise AND)
|
if BOTH bits are 1 then result is 1 else its 0
|
p & q = 0 (0000 0000)
|
0000 1010 &
0000 0100
------------
0000 0000
|
|
(Bitwise OR)
|
if ANY bit is 1, result is 1 else 0
|
p | q = 14 (0000 1110)
|
0000 1010 |
0000 0100
------------
0000 1110
|
~
(Bitwise NOT)
|
negate/invert all bits
|
~p = -11 (1111 0101)
|
~ 0000 1010
------------
1111 0101
|
^
(Bitwise XOR)
|
if ONLY one of the bit is 1, result is 1 else 0 (1^1=0)
|
Suppose,
a = 5 ( 0000 0101)
b = 3 ( 0000 0011)
Then
a ^ b = 6 (0000 0110)
Note: a | b = 7 (0000 0111)
|
0000
0101 ^
0000 0011
------------
0000 0110
|
>>
(Bitwise right shift)
|
shift each bit towards right
|
p >> 1 = 5 (0000 0101)
(Shifts every bit by 1 position to right)
|
0000 1010 >> 1
------------
0000 0101
|
<<
(Bitwise left shift)
|
shift each bit towards left
|
p << 2 = 40 (0010 1000)
(Shifts every bit by 2 positions to left)
|
0000 1010 << 2
------------
0010 1000
|
Example code (Bitwise left shift):
a=2;
std::cout<<"a
= "<<(a<<3);
Output:
a = 16
|
OPERATOR PRECEDENCE
Operator
precedence is the rule followed by programming languages
in deciding the priority of operations in an expression having multiple
operators. Eg: In the expression 5+2*9 the multiplication operator (*) is given top priority,
followed by the addition operator (+). Hence the expression 5+2*9 would
evaluate to 23.
However, precedence levels of operators can
be restructured by grouping them using parenthesis (round brackets). Grouping defines the precedence order in which operators are
evaluated in an expression. For example, the expression 5+2*9 gives 23. After grouping
it to (5+2)*9, the answer would be 63.
From greatest to lowest priority, the order of operator
precedence follows the rules as specified in the chart:
PROGRAM 13 (Brain Teaser Program): Develop a simple billing system for the Kerala House Restaurant. Items sold: Egg Porota (Rs. 80), Kerala Meals
(Rs. 100). If customer is student, then discount = 50%, else discount = 25%. GST
of 18% after discount, has to be added as tax.
Challenge: Use compound assignment
operator, scope resolution operator, ternary operator, comma
operator and preprocessor directives wherever necessary.
|
#include <iostream> #include
<string> using
namespace std; int
discount = 25;
int
main () { #define EP 80 // Egg Porota #define ML 100 // Kerala Meals #define gst .18 // 18% GST int fcode, scode, pcode; int discount = 50; float cost=0, tot=0, tax=0, price; string s; cout<<"###
Food Code ### \n\nEgg Porotta: 1 \nKerala Meal: 2"; cout<<"\n\nEnter Food Code:
"; cin>>fcode;
s = fcode == 1 ? "Egg Porota" :
"Kerala Meals"; cout<<"\nEnter 1 for Student
(else any number): "; cin>>scode; cost = ((fcode == 1 ? cost+=EP : cost +=
ML), price=cost, (scode == 1 ? cost-=(cost*discount)/100 :
cost-=(cost*::discount)/100)); tax = cost*gst; tot = cost+tax; cout<<
"\nItem Name :
"<< s; cout<< "\nItem Price : Rs. "<< price; cout<< "\nDiscounted Price : Rs.
"<< cost; cout<< "\nTax (GST) : Rs. "<< tax; cout<<
"\n-------------------------------"; cout<< "\nTotal Cost : Rs. "<< tot;
} |
Output (screenshots of all the 4 conditions can be referred here)
CHAPTER
EVALUATION EXERCISE
A) Choose the most appropriate
answer (1 mark)
1.
! (NOT) is a _____________ operator.
(a)
logical (b) type casting (c) assignment (d) pointer
2.
A variable is a/an ____________
(a)
operator (b) operand (c)
expression (d) keyword
3.
Ternary operator generally works with ____________ operands.
(a)
one (b) two (c)
three (d) none
4.
sizeof(float) would return ____________ bytes.
(a)
1 (b) 2 (c) 4 (d) 8
5.
If a 4-bit binary is 1010, then its bit-wise complement is ____________
(a)
0101 (b) 1100 (c) 1011 (d)
1111
6.
For expression (a=3)=(b=9)=(c=5) what would be a, b, c ?
(a)
3, 9, 5 (b) 3, 3, 3 (c) 5, 5, 5 (d)
syntax error
7.
If a=b=c=2, the expression c = (a=b--) results in ____________ values for a,b,c
(a)
2,2,2 (b) 1,1,1 (c) 1,1,2 (d)
2,1,2
8.
If a=5, b=10, c=4, the expression a+=((b/=a)*(c%=2)) results in ____________
values for a,b,c.
(a)
19,12,4 (b) 5,2,0 (c) 5,0,0 (d)
24,12,2
9.
Among logical operators ____________ is a unary operator.
(a)
AND (b) OR (c) NOT (d) a,b,c
10.
____________ operator joins any number of expressions and executes them in
sequence.
(a)
Comma (b) Ternary (c) Logical (d)
a,b,c
11. What will be m, n for these two conditions:
int m=4 ;
m = ++m + ++m;
int n=4 ;
n = n++ + n++;
(a) 10, 8 (b) 10, 10 (c)
9, 12 (d) 12, 9
ANSWERS
1)
a 2) b 3)
c 4) c 5) a 6) c 7) d 8)
b 9) c 10)
a 11) d
B) Fill in the blanks (1 mark)
1.
15 % 6 = ____________
2.
____________ returns the size of a data type in Bytes.
3.
"(double)i" performs ____________ operation.
4.
One's complement of decimal 2 is ____________
5.
____________ is the bitwise right shift operator.
6.
What is value of "a" for ternary expression 10==10 ? a=28 : a=45
7.
std::cout makes use of ____________ operator.
8.
____________ operator points to memory address of a variable.
9.
In an expression with multiple operators ____________ defines the precedence in
which operators are evaluated.
10.
If a = 12 (0000 1100) then bitwise operation (a<<3) gives 8-bit binary
value ____________
ANSWERS
1) 3 2) sizeof
operator 3) typecast
4) 1101 5) >>= 6) 28
4) 1101 5) >>= 6) 28
7) scope resolution 8) address (&) 9) grouping
10) 0110 0000 (96)
C) State whether True or False
(1 mark)
1.
In the expression 10i+2j, 'i' is operand and also a variable.
2.
Pre decrement operator is a suffix.
3.
(float)j and float(j) execute same operation.
4.
One’s Complement Operator is represented by ~
5.
The expression, (9<7 || 12>9) evaluates to boolean TRUE.
ANSWERS
1)
True 2) False 3) True 4) True 5)
True
D) Short answer questions (5
marks)
2.
Differentiate between increment and decrement operators.
3.
List all arithmetic and bitwise operators in compound assignment.
4.
Brief on scope resolution operator.
5.
What is operator precedence? Give an example.
E) Subjective questions (10
marks)
1.
Describe any 5 types of operators with relevant examples.
2. What is a bitwise operator? Explain any 3
bitwise operators with examples.
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