1. What is an Operator?

An operator is a symbol used to perform an operation on one or more values or variables.

Example

int a = 10;
int b = 5;
 
int result = a + b;

Here:

• a and b are operands.
• + is an operator.
• a + b is an expression.
• The result is 15.

2. What is an Expression?

An expression is a combination of values, variables, and operators that produces a result.

Examples

a + b

marks >= 50

age >= 18 && age <= 60

Each of these expressions produces a result.

3. Types of Operators Based on Number of Operands

Operators can be classified according to the number of operands they work with.

3.1 Unary Operators

A unary operator works with one operand.

Examples

x++;

-x;

!isStudent;

Only one variable/value is involved.

Common Unary Operators

3.2 Binary Operators

A binary operator works with two operands.

Example

a + b

Here:

• a → first operand
• + → operator
• b → second operand

Other examples:

a - b
a * b
a > b
a == b

Remember

Unary → one operand

x++;

Binary → two operands

x + y;

4. Types of C++ Operators

The main operators we will study are:

1. Arithmetic Operators
2. Assignment Operator
3. Compound Assignment Operators
4. Increment and Decrement Operators
5. Relational Operators
6. Logical Operators

5. Arithmetic Operators

Arithmetic operators are used to perform mathematical calculations.

Example

int a = 10;
int b = 3;
 
cout << a + b;   // 13
cout << a - b;   // 7
cout << a * b;   // 30
cout << a / b;   // 3
cout << a % b;   // 1

Important Point: / Division Operator

The / operator is used for division.

The result depends on the data type of the operands.

1. Both Operands are int

If both operands are integers, C++ performs integer division.

int a = 10;
int b = 3;
 
cout << a / b;

Output:

3

Although mathematically:

10 ÷ 3 = 3.3333...

C++ gives:

3

because both a and b are int.

Important: The decimal part is removed when integer division is performed.

2. One Operand is float

If at least one operand is a float, the division produces a decimal result.

float a = 10;
int b = 3;
 
cout << a / b;

Output:

3.33333

Here:

float / int → decimal result

3. Both Operands are float

float a = 10;
float b = 3;
 
cout << a / b;

Output:

3.33333

Here:

float / float → decimal result

4. Using double

double can also be used for decimal calculations.

double a = 10;
double b = 3;
 
cout << a / b;

Output:

3.33333

Remember

Important Rule

If both operands are int, the result of / is integer division. If at least one operand is a floating-point type (float or double), the result can contain decimal values.

Important Point: % Remainder Operator

The % operator gives the remainder after integer division.

int a = 10;
int b = 3;
 
cout << a % b;

Output:

1

Because:

10 ÷ 3 = 3 remainder 1

Therefore:

10 / 3 = 3
10 % 3 = 1

Another Example

int a = 20;
int b = 6;
 
cout << a / b << endl;
cout << a % b << endl;

Output:

3
2

Because:

20 ÷ 6 = 3 remainder 2

Remember

/  → gives the quotient
%  → gives the remainder

For example:

17 / 5 = 3
17 % 5 = 2

6. Assignment Operator

The assignment operator is:

=

It is used to assign a value to a variable.

Example

int age = 20;

This means:

Store the value 20 in the variable age.

Another example:

int x = 10;
 
x = 25;

Now:

x = 25

Important

Do not confuse:

=

with:

==

= means assignment.

== means comparison.

Example:

x = 10;    // Assign 10 to x
x == 10;   // Check whether x is 10

7. Compound Assignment Operators

Compound assignment operators provide a shorter way to update a variable.

Example

Instead of:

x = x + 5;

we can write:

x += 5;

Both have the same effect.

Common Compound Assignment Operators

Example

int marks = 70;
 
marks += 5;

Now:

marks = 75

8. Increment Operator ++

The increment operator increases a value by 1.

int x = 5;
 
x++;

Now:

x = 6

It is equivalent to:

x = x + 1;

There are two forms:

x++;

Post-increment

and:

++x;

Pre-increment

Both increase the value by 1. The difference becomes important when the operator is used inside a larger expression.

9. Decrement Operator --

The decrement operator decreases a value by 1.

int x = 5;
 
x--;

Now:

x = 4

It is equivalent to:

x = x - 1;

There are two forms:

x--;

Post-decrement

and:

--x;

Pre-decrement

10. Relational Operators

Relational operators are used to compare two values.

The result of a comparison is either:

true

or:

false

Relational Operators

Example

int marks = 75;
 
cout << (marks >= 50);

The expression is:

marks >= 50

Since 75 is greater than 50, the result is:

true

11. Logical Operators

Logical operators are used to combine or reverse conditions.

There are three main logical operators:

11.1 AND Operator &&

The && operator returns true when both conditions are true.

Example

age >= 18 && marks >= 50

This means:

Age must be 18 or above AND marks must be 50 or above.

11.2 OR Operator ||

The || operator returns true when at least one condition is true.

Example

day == 6 || day == 7

This means:

Day is 6 OR day is 7.

11.3 NOT Operator !

The ! operator reverses a Boolean value or condition.

Example

bool isStudent = true;
 
cout << !isStudent;

The result becomes:

false

Because ! changes true to false and false to true.

12. Operators in if Statements

Operators are commonly used to create conditions in if statements.

Example 1

int marks = 75;
 
if (marks >= 50)
{
    cout << "Pass";
}

Here:

marks >= 50

is a condition/expression using a relational operator.

Example 2

int age = 20;
int marks = 75;
 
if (age >= 18 && marks >= 50)
{
    cout << "Eligible";
}

Here:

• >= → Relational operator
• && → Logical operator
• age >= 18 → First condition
• marks >= 50 → Second condition

13. Operator Summary

14. Quick Revision

Operator

A symbol used to perform an operation.

Operand

A value or variable on which an operator works.

Expression

A combination of values, variables, and operators that produces a result.

Unary

Works with one operand.

x++;

Binary

Works with two operands.

x + y;

Arithmetic

Used for calculations.

+  -  *  /  %

Relational

Used for comparison.

>  <  >=  <=  ==  !=

Logical

Used to combine or reverse conditions.

&&  ||  !

Assignment

Used to assign a value.

=

Compound Assignment

Used to update a value in a shorter way.

+=  -=  *=  /=  %=

Increment / Decrement

Used to increase or decrease a value by 1.

++  --

Examples

C++ Example: Prefix and Postfix Increment Operators

Question: Write a C++ program to demonstrate the difference between prefix (++a) and postfix (a++) increment operators.

#include <iostream>
using namespace std;
 
int main() {
    int a = 5;
    int b = 5;
 
    cout << "Initial values: a = " << a << ", b = " << b << endl;
 
    // 1. Prefix increment: ++a
    // The value is incremented first, then used
    int prefixResult = ++a;
    cout << "After prefix increment (++a): a = " << a << ", result = " << prefixResult << endl;
 
    // 2. Postfix increment: b++
    // The value is used first, then incremented
    int postfixResult = b++;
    cout << "After postfix increment (b++): b = " << b << ", result = " << postfixResult << endl;
 
    return 0;
}

Explanation:

1. Prefix Increment (++a):

   • Increments the value of the variable before using it in an expression.
   • Example: ++a → first increase a by 1, then use the new value.

2. Postfix Increment (a++):

   • Uses the current value of the variable in an expression first, then increments it.
   • Example: a++ → use the value of a, then increase it by 1.

3. Output Understanding:

   Initial values: a = 5, b = 5
   After prefix increment (++a): a = 6, result = 6
   After postfix increment (b++): b = 6, result = 5
   

C++ Example: Arithmetic Operators

Question: Write a C++ program to demonstrate the use of arithmetic operators in C++.

#include <iostream>
using namespace std;
 
int main() {
    int a = 15;
    int b = 4;
 
    cout << "Values: a = " << a << ", b = " << b << endl;
 
    // 1. Addition (+)
    cout << "a + b = " << a + b << endl;
 
    // 2. Subtraction (-)
    cout << "a - b = " << a - b << endl;
 
    // 3. Multiplication (*)
    cout << "a * b = " << a * b << endl;
 
    // 4. Division (/)
    cout << "a / b = " << a / b << " (integer division)" << endl;
 
    // 5. Modulus (%) - remainder of division
    cout << "a % b = " << a % b << endl;
 
    // 6. Increment (++) - increases value by 1
    a++;
    cout << "After increment, a = " << a << endl;
 
    // 7. Decrement (--) - decreases value by 1
    b--;
    cout << "After decrement, b = " << b << endl;
 
    return 0;
}

Explanation for Beginners:

1. Arithmetic operators are used to perform mathematical operations on numbers.

2. Operators used in the example:

   • + Addition
   • - Subtraction
   • * Multiplication
   • / Division
   • % Modulus (remainder)
   • ++ Increment
   • -- Decrement

3. Integer division truncates the decimal part. Example: 15 / 4 = 3.

C++ Example: Assignment Operator and Arithmetic Assignment Operators

Question: Write a C++ program to demonstrate the use of assignment operators in C++.

#include <iostream>
using namespace std;
 
int main() {
    int a = 10; // Simple assignment (=)
    int b = 5;
 
    cout << "Initial values: a = " << a << ", b = " << b << endl;
 
    // 1. Addition assignment (+=)
    a += b; // equivalent to a = a + b
    cout << "After a += b, a = " << a << endl;
 
    // 2. Subtraction assignment (-=)
    a -= b; // equivalent to a = a - b
    cout << "After a -= b, a = " << a << endl;
 
    // 3. Multiplication assignment (*=)
    a *= b; // equivalent to a = a * b
    cout << "After a *= b, a = " << a << endl;
 
    // 4. Division assignment (/=)
    a /= b; // equivalent to a = a / b
    cout << "After a /= b, a = " << a << endl;
 
    // 5. Modulus assignment (%=)
    a %= b; // equivalent to a = a % b
    cout << "After a %= b, a = " << a << endl;
 
    return 0;
}

Explanation for Beginners:

1. Assignment operators are used to store values in variables and optionally perform an operation at the same time.

2. Examples:

   • = → simple assignment
   • += → add right value to left variable and assign result
   • -= → subtract right value from left variable and assign result
   • *= → multiply left variable by right value and assign result
   • /= → divide left variable by right value and assign result
   • %= → find remainder and assign result