Operators in C++

February 21, 2023

Operators in C++

C++ supports a rich set of operators. Operators say the compiler to perform mathematical and logical computations on the data stored in memory. Here, on this page, we will discuss different operators in C++.

Operators

C++ library has the following –

Arithmetic Operators
Relational Operators
Logical Operators
Bitwise Operators
Assignment Operators
Misc Operators

Arithmetic Operators

For a = 100 and b = 50

Operator	Description	Example
+	To add two operands	a + b = 150
–	To subtract two operands	a – b = 50
*	To multiply two operands	a * b = 5000
/	To divide two operands	a / b = 2
%	Modulus operator : To find remainder	a % b = 0 10 % 4 = 2
++	Increment Operator : To increase value by 1	a++ = 101
—	Decrement Operator : To decrease value by 1	a– = 99

Example of above operations –

Run

#include <iostream>
using namespace std;

int main() {
    int a, b;
    a = 20;
    b = 3;

    // prints the sum of a & b
    cout << "a + b = " << (a + b) << endl;

    // prints the difference between a & b
    cout << "a - b = " << (a - b) << endl;

    // prints the multiplication of a & b
    cout << "a * b = " << (a * b) << endl;

    // prints the division of a by b
    // result 6.33 reduced to 6 since both numbers are int result will be int
    cout << "a / b = " << (a / b) << endl;

    // prints the remainder when a is divided by b
    cout << "a % b = " << (a % b) << endl;

    return 0;
}

Output:

a + b = 23
a - b = 17
a * b = 60
a / b = 6
a % b = 2

Another interesting fact to know about division operators would be - In C++, output may change based on if combinations of operands in int/double. Example following would be printed if operands as changed as -

5/2 is 2
5.0 / 2 is 2.5
5 / 2.0 is 2.5
5.0 / 2.0 is 2.5

Relational Operators

The output of the relational operators is always in the form of –
- 0 (false)
- 1 or a positive number (true)
If the condition is satisfied gives 1 and if the condition is false it gives 0

Operator	Name	Example	Result
>	Greater than	10 > 5	true
>=	Greater than or Equal	10 >=5 5 >= 5 2 >= 5	true true false
<	Lesser than	10 < 5	false
<=	Lesser than or Equal	10 <= 5 5 <= 5 2 <= 5	false true true
==’	is equals	10 == 10 100 = 20	true false
!=0	is not equals	10 != 10 100 != 20	false true

C++ program demonstrating Relational operators

Run

#include<iostream> 
using namespace std;

int main() {
    int a, b;
    a = 10;
    b = 5;
    
    bool result;

    result = (a == b);   // false
    cout << "10 == 5 is " << result << endl;

    result = (a != b);  // true
    cout << "10 != 5 is " << result << endl; result = a > b;   // true
    cout << "10 > 5 is " << result << endl;

    result = a < b;   // false
    cout << "10 < 5 is " << result << endl; result = a >= b;  // true
    cout << "10 >= 5 is " << result << endl;

    result = a <= b;  // false
    cout << "10 <= 5 is " << result << endl;

    return 0;
}

Output

10 == 5 is 0
10 != 5 is 1
10 > 5 is 1
10 < 5 is 0 10 >= 5 is 1
10 <= 5 is 0

Logical Operators

The output of the logical operators is always in the form of 0 (false) and 1 (true)
A logical operator is a valid combination of values, variables & relational expressions

Operator	Example	Description
&&	A && B expression1 && expression 2	Logical AND. True only if all the operands are true (non zero)
\|\|	A \|\| B expression1 \|\| expression 2	Logical OR. True only if any the operands are true (non zero)
!	!A	Logical NOT Use to reverses the logical state of its operand.

Logical approach to demonstrate

Imagine,
a = 15
b = 20

// both should be true
(a > 5) && (b > 10) // true && true = true
(a > 5)  && (b < 10) // true && false = false
(a < 5) && (b > 10) // false && true = false
(a < 5)  && (b < 10) // false && false = false // any one or more can be true (a > 5) || (b > 10) // true || true = true (a > 5) || (b < 10) // true || false = true (a < 5) || (b > 10) // false || true = true (a < 5) || (b < 10) // false || false = false !(a < 5) // !(false) = true !(a > 5) // !(true) = false

The following code will help us understand more about these –

Run

#include<iostream>
using namespace std;

int main() {
    int a = 20;
    int b = 10;
    bool output;

    output = (a > 5) && (b > 5);     // true
    cout << "(a > 5) && (b > 5) is " << output << endl; output = (a > 0) && (b >= 10); // true
    cout << "(a > 0) && (b >= 10) is " << output << endl;
    output = (a != 0) && (b == 0); // false
    cout << "(a != 0) && (b == 0) is " << output << endl;
    output = (a != b) || (a < b); // true 
    cout << "(a != b) || (a < b) is " << output << endl;
    output = (a < b) || (b > 10); // false
    cout << "(a < b) || (b > 10) is " << output << endl; // both are non zero numbers so both will be true
    output = (a) && (b); // true 
    cout << "(a) && (b) is " << output << endl; 
    output = !(a == 20); // false 
    cout << "!(a == 20) is " << output << endl;
    output = !(a < 0); // true 
    cout << "!(a < 0) is " << output << endl; // doing not operation on a non zero value will result to 0 & !(0) // !(a) => !(20) => !(true) => false output = !(a); 
    // false 
    cout << "!(a) is " << output << endl;
    return 0; 
}

Output

(a > 5) && (b > 5) is 1
(a > 0) && (b >= 10) is 1
(a != 0) && (b == 0) is 0
(a != b) || (a < b) is 1
(a < b) || (b > 10) is 0
(a) && (b) is 1
!(a == 20) is 0
!(a < 0) is 1
!(a) is 0

Loop Types in C++

Decision Making in C++

Array in C++

String in C++

Function in C++

Bitwise Operators

Bitwise operators work on individual bits of a number. All numbers are stored in binary format in c++.

Example: 10 -> 00001010

Bitwise operators will work on these binary bits. Following are the operators –

Bitwise AND
Bitwise OR
Bitwise XOR
Bitwise Not or 1’s compliment
Bitwise shift left
Bitwise Shirt right

Following is the truth table for common operations –

a	b	a & b	a \| b	a ^ b
0	0	0	0	0
0	1	0	1	1
1	0	0	1	1
1	1	1	1	0

Let us assume two numbers A: 11 and B: 7. The binary would be –

A: 0000 1011
B: 0000 0111

The following will be results on applying various operations on individual digits –

A & B: 0000 0011
A | B: 0000 1111
A ^ B: 0000 1100
~A: 1111 0100
A << 2: 0010 1100
B >> 2: 0000 0010

Which is 3 in decimal

Operator	Description	Examples
&	Bitwise AND Applies & i.e. AND operator on individual bits for two operands	A & B: 0000 0011
\|	Bitwise OR Applies \| i.e. OR operator on individual bits for two operands	A \| B: 0000 1111 Which is 15 in decimal
^	Bitwise XOR Applies \| i.e. XOR operator on individual bits for two operands	A ^ B: 0000 1100 Which is 12 in decimal
~	Bitwise NOT Applies 1 compliment or bitwise NOT on a single operand	~A: 1111 0100 Which is -12 in decimal (Negative numbers are stored in 2’s compliment, 1st bit shows its negative)
<<	Bitwise SHIFT Left Shifts all successive bits towards left by ‘x’ bits	A << 2: 0010 1100 Which is 42 in DecimalAll bits of A: 0000 1011 shifted 2 places left
>>	Bitwise SHIFT Right Shifts all successive bits towards right by ‘x’ bits	A << 2: 0000 0010 Which is 2 in decimalAll bits of A: 0000 1011 shifted 2 places right

The following program shows code for the same –

Run

#include<iostream> 
using namespace std;

int main() {
    int a = 11; // 0000 1011
    int b = 7; // 0000 0111
    
    cout << "(a & b)  : " << (a & b) << endl;
    cout << "(a | b)  : " << (a | b) << endl;
    cout << "(a ^ b)  : " << (a ^ b) << endl;
    cout << "(~a)     : " << ~a << endl;
    cout << "(a << 2) : " << (a << 2) << endl;
    cout << "(a >> 2) : " << (a >> 2) << endl;

    return 0;
}

Output

(a & b)  : 3
(a | b)  : 15
(a ^ b)  : 12
(~a)     : -12
(a << 2) : 44 
(a >> 2) : 2

Assignment Operators

Assignment operators are used for shortening mathematical assignments.

Operator	Description	Examples
=	Simple Assignment Operator	c = a + b
+=	Shorter form for addition assignment	a = a + b can be written as a += b
-=	Shorter form for subtraction assignment	a = a – b can be written as a -= b
*=	Shorter form for multiplication assignment	a = a * b can be written as a *= b
/=	Shorter form for division assignment	a = a / b can be written as a /= b
%=	Shorter form for modulo assignment	a = a % b can be written as a %= b
<<=	Shorter form for shift left assignment	A <<= 2 can be written as A = A << 2
>>=	Shorter form for shift right assignment	A >>= 2 can be written as A = A >> 2
&=	Shorter form for bitwise AND assignment	a = a & b can be written as a &= b
^=	Shorter form for bitwise XOR assignment	a = a ^ b can be written as a ^= b
\|=	Shorter form for bitwise OR assignment	a = a \| b can be written as a \|= b

Code to demonstrate assignment operators –

Run

#include<iostream>
using namespace std;

int main() {
    int a = 10;
    int b = 5;

    a += b; // same as a = a + b | a becomes 15
    cout << a << endl;
    
    a /= b; // same as a = a / b | a becomes 3
    cout << a << endl;

    return 0;
}

Output

15
3

Ternary Operator

The conditional operator is a decision-making operator whose statement is evaluated based on the test condition

Syntax:

(Test condition)? (Do this if True) : (Do this is False)

If the condition is true statement 1 is evaluated and if it is false, statement 2 is evaluated

Test whether a number is even or odd using the ternary operator

Run

#include<iostream> 
using namespace std;

int main()
{
    int n;
    cout << "Enter a number:" << endl; cin >> n;
    
    //using ternary operator
    // modulo operator to check remainder
    (n % 2 == 0) ? cout << "Even": cout << "Odd";
    
    return 0;
}

Output

Enter a number:
10
Even

Find the maximum of three numbers using the ternary operator

Run

#include<iostream> 
using namespace std;

int main()
{
    int a, b, result;

    cout<<"Enter two numbers :"; cin >> a >> b;
    
    result = a > b ? a : b;
    cout<<"Larger: "<< result;

    return 0;
}

O/P

Enter two numbers :10 20
Larger: 20

Comma Operator

The comma operator is a special operator which evaluates statements from left to right and returns the rightmost expression as the final result

C++ program to demonstrate comma operator

Run

#include&t;iostream> 
using namespace std;

int main()
{
    int a = 1, b = 2, c;
    
    c = (a = a + 2, b = a + 3, b = a + b);
    // comma operator association is left to right so
    // left operations happen first and then right
    // initially a = a + 2 is evaluated (a = 1 + 2) which makes a : 3 then 
    // b = a + 3 is evaluated (b = 3 + 3) which makes b : 6 
    // finally b = a + b is evaluated (b = 3 + 6) which b : 9
    // this final value is returned to assignment c = return value 9
    
    cout << c; // 9
    
    return 0;
}

Output

Increment/Decrement operators

The ++ and — operators add 1 and subtract 1 from the existing value at the memory location

Post increment/decrement

In a single execution line assignment may happen first and increment/decrement may happen later

Run

#include<iostream>
using namespace std;

int main()
{
    int a = 10;
    int b = 20;
    int result;
    
    // demonstrating post increment operator
    
    // value is assigned first and then incremented later
    result = a++; 
    cout << "a: " << a << ", res: " << result << endl;
    
    // value is assigned first and then incremented later
    result = b--; 
    cout << "b: " << b << ", res: " << result << endl;
    
    return 0;
}

Output

a: 11, res: 10
b: 19, res: 20

Pre increment/decrement

Increment happens first and assignment happens later

Run

#include<iostream> 
using namespace std;

int main()
{
    int a = 10;
    int b = 20;
    int result;
    
    // demonstrating pre increment operator
    
    // value is incremented first and assigned later
    result = ++a; 
    cout << "a: " << a << ", res: " << result << endl;
    
    // value is assigned first and then incremented later
    result = --b; 
    cout << "b: " << b << ", res: " << result << endl;
    
    return 0;
}

Output

a: 11, res: 11
b: 19, res: 19

Cleary understand the diffeernce between pre and post inc/dec operators

Below can be an interesting program to learn new things –

Run

#include<iostream> 
using namespace std;

int main()
{
    int a = 5;
    
    cout << "++a :" << ++a << "\ta: " << a << endl;
    cout << "--a :" << --a << "\ta: " << a << endl;
    cout << "a++: " << a++ << "\ta: " << a << endl;
    cout << "a--: " << a-- << "\ta: " << a << endl;
    
    return 0;
}

Output

++a :6	a: 6
--a :5	a: 5
a++: 5	a: 6
a--: 6	a: 5

Precedence

Operator precedence gives priorities to operators while evaluating an expression

For example: when 2 * 3 + 2 is evaluated output is 8 but not 12 because the * operator is having more priority than + hence 2 * 3 is evaluated first followed by 6 + 2.

Operator precedence table

The operator precedence table gives the detailed list of priorities for each and every operator
Operators are listed from higher priority to lower

Precedence	Operator	Description	Associativity
1	`::`	Scope resolution	Left-to-right
2	`++` `--`	Suffix/postfix increment and decrement
	`type()` `type{}`	Function-style typecast
	`()`	Function call
	`[]`	Array subscripting
	`.`	Element selection by reference
	`->`	Element selection through pointer
3	`++` `--`	Prefix increment and decrement	Right-to-left
	`+` `-`	Unary plus and minus
	`!` `~`	Logical NOT and bitwise NOT
	`(type)`	C-style type cast
	`*`	Indirection (dereference)
	`&`	Address-of
	`sizeof`	Size-of
	`new`, `new[]`	Dynamic memory allocation
	`delete`, `delete[]`	Dynamic memory deallocation
4	`.` `->`	Pointer to member	Left-to-right
5	`*` `/` `%`	Multiplication, division, and remainder
6	`+` `-`	Addition and subtraction
7	`<<` `>>`	Bitwise left shift and right shift
8	`<` `<=`	For relational operators < and ≤ respectively
8	`>` `>=`	For relational operators > and ≥ respectively
9	`==` `!=`	For relational = and ≠ respectively
10	`&`	Bitwise AND
11	`^`	Bitwise XOR (exclusive or)
12	`\|`	Bitwise OR (inclusive or)
13	`&&`	Logical AND
14	`\|\|`	Logical OR
15	`?:`	Ternary conditional operator	Right-to-left
	`=`	Direct assignment (provided by default for C++ classes)
	`+=` `-=`	Assignment by sum and difference
	`*=` `/=` `%=`	Assignment by product, quotient, and remainder
	`<<=` `>>=`	Assignment by bitwise left shift and right shift
	`&=` `^=` `\|=`	Assignment by bitwise AND, XOR, and OR
16	`throw`	Throw operator (for exceptions)
17	`,`	Comma	Left-to-right

Example1

Evaluate 5*4+(3+2)

Parenthesis is having the highest priority
5*4+5
Among * and +,* is having the highest priority
20 + 5= 25 is the final output

Example 2

Arithmetic operators for having higher priority than relational operators

Observe the difference With Parenthesis and without Parenthesis

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Operators in C++

Operators in C++

Operators

Arithmetic Operators

Output:

Relational Operators

C++ program demonstrating Relational operators

Output

Logical Operators

Logical approach to demonstrate

Output

Bitwise Operators

Output

Assignment Operators

Output

Ternary Operator

Syntax:

Test whether a number is even or odd using the ternary operator

Output

Find the maximum of three numbers using the ternary operator

Comma Operator

C++ program to demonstrate comma operator

Output

Increment/Decrement operators

Post increment/decrement

Output

Pre increment/decrement

Output

Cleary understand the diffeernce between pre and post inc/dec operators

Output

Precedence

Operator precedence table

Example1

Example 2

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