Operators in C++

C++ operators are the symbols that operate on values to perform specific mathematical or logical computations on given values. They are the foundation of any programming language.

Example:

#include <iostream>
using namespace std;
int main() {
  
	int a = 10 + 20;
  
    cout << a;
    return 0;
}

30

Explanation: Here, '+' is an addition operator and does the addition of 10 and 20 operands and return value 30 as a result.

C++ Operator Types

C++ operators are classified into 6 types on the basis of type of operation they perform:

1. Arithmetic Operators

Arithmetic operators are used to perform arithmetic or mathematical operations on the operands. For example, '+' is used for addition.

Example:

#include <bits/stdc++.h>
using namespace std;

int main() {
    int a = 8, b = 3;

    // Addition
    cout << "a + b = " << (a + b) << endl;
  
    // Subtraction
    cout << "a - b = " << (a - b) << endl;
  
    // Multiplication
    cout << "a * b = " << (a * b) << endl;
  
    // Division
    cout << "a / b = " << (a / b) << endl;
  
    // Modulo
    cout << "a % b = " << (a % b) << endl;
  
    // Increament
    cout << "++a = " << ++a << endl;
  
    // Decrement
    cout << "b-- = " << b--;
    
    return 0;
}

a + b = 11
a - b = 5
a * b = 24
a / b = 2
a % b = 2
++a = 9
--b = 2

Important Points:

• The Modulo operator (%) operator should only be used with integers. Other operators can also be used with floating point values.
• ++a and a++, both are increment operators, however, both are slightly different. In ++a, the value of the variable is incremented first and then it is used in the program. In a++, the value of the variable is assigned first and then it is incremented. Similarly happens for the decrement operator.

You may have noticed that some operator works on two operands while other work on one. On the basis of this operators are also classified as:

• Unary: Works on single operand.
• Binary: Works on two operands.
• Ternary: Works on three operands.

2. Relational Operators

Relational operators are used for the comparison of the values of two operands. For example, '>' check right operand is greater.

Example

#include <bits/stdc++.h>
using namespace std;

int main() {
    int a = 6, b = 4;

    // Equal operator
    cout << "a == b is " << (a == b) << endl;
  
    // Greater than operator
    cout << "a > b is " << (a > b) << endl;
  
    // Greater than Equal to operator
    cout << "a >= b is " << (a >= b) << endl;
  
    //  Lesser than operator
    cout << "a < b is " << (a < b) << endl;
  
    // Lesser than Equal to operator
    cout << "a <= b is " << (a <= b) << endl;
  
    // Not equal to operator
    cout << "a != b is " << (a != b);

    return 0;
}

a == b is 0
a > b is 1
a >= b is 1
a < b is 0
a <= b is 0
a != b is 1

Note: 0 denotes false and 1 denotes true.

3. Logical Operators

Logical operators are used to combine two or more conditions or constraints or to complement the evaluation of the original condition in consideration. The result returns a Boolean value, i.e., true or false.

Example:

#include <bits/stdc++.h>
using namespace std;

int main() {
    int a = 6, b = 4;

    // Logical AND operator
    cout << "a && b is " << (a && b) << endl;
  
    // Logical OR operator
    cout << "a || b is " << (a || b) << endl;
  
    // Logical NOT operator
    cout << "!b is " << (!b);

    return 0;
}

a && b is 1
a || b is 1
!b is 0

4. Bitwise Operators

Bitwise operators are works on bit-level. So, compiler first converted to bit-level and then the calculation is performed on the operands.

Note: Only char and int data types can be used with Bitwise Operators.

Example:

#include <bits/stdc++.h>
using namespace std;

int main() {
    int a = 6, b = 4;

    // Binary AND operator
    cout << "a & b is " << (a & b) << endl;

    // Binary OR operator
    cout << "a | b is " << (a | b) << endl;

    // Binary XOR operator
    cout << "a ^ b is " << (a ^ b) << endl;

    // Left Shift operator
    cout << "a<<1 is " << (a << 1) << endl;

    // Right Shift operator
    cout << "a>>1 is " << (a >> 1) << endl;

    // One’s Complement operator
    cout << "~(a) is " << ~(a);

    return 0;
}

a & b is 4
a | b is 6
a ^ b is 2
a<<1 is 12
a>>1 is 3
~(a) is -7

5. Assignment Operators

Assignment operators are used to assign value to a variable. We assign the value of right operand into left operand according to which assignment operator we use.  

Example:

#include <bits/stdc++.h>
using namespace std;

int main() {
    int a = 6, b = 4;

    // Assignment Operator.
    cout << "a = " << a << endl;
  
    //  Add and Assignment Operator.
    cout << "a += b is " << (a += b) << endl;
  
    // Subtract and Assignment Operator.
    cout << "a -= b is " << (a -= b) << endl;
  
    //  Multiply and Assignment Operator.
    cout << "a *= b is " << (a *= b) << endl;
  
    //  Divide and Assignment Operator.
    cout << "a /= b is " << (a /= b);

    return 0;
}

a = 6
a += b is 10
a -= b is 6
a *= b is 24
a /= b is 6

6. Ternary or Conditional Operators

Conditional operator returns the value, based on the condition. This operator takes three operands, therefore it is known as a Ternary Operator.

Syntax:

Expression1 ? Expression2 : Expression3

In the above statement:

• The ternary operator ? determines the answer on the basis of the evaluation of Expression1.
• If Expression1 is true, then Expression2 gets evaluated.
• If Expression1 is false, then Expression3 gets evaluated.

Example:

#include <bits/stdc++.h>
using namespace std;

int main() {
    int a = 3, b = 4;

    // Conditional Operator
    int result = (a < b) ? b : a;
    cout << "The greatest number "
         "is " << result;

    return 0;
}

The greatest number is 4

Miscellaneous Operators

Apart from these operators, there are a few operators that do not fit in any of the above categories. These are:

1. sizeof Operator

sizeof operator is a unary operator used to compute the size of its operand or variable in bytes. For example,

sizeof (char);
sizeof (var_name);

2. Comma Operator (,)

Comma operator is a binary operator that is used for multiple purposes. It is used as a separator or used to evaluate its first operand and discards the result; it then evaluates the second operand and returns this value (and type).

int n = (m+1, m-2, m+5);
int a, b, c;

6. Addressof Operator (&)

Addressof operator is used to find the memory address in which a particular variable is stored. In C++, it is also used to create a reference.

&var_name;

5. Dot Operator(.)

Dot operator is used to access members of structure variables or class objects using their object names.

obj . member;

3. Arrow Operator

Arrow operator is used to access the variables of classes or structures through its pointer.

sptr -> member;

4. Casting Operators

Casting operators are used to convert the value of one data type to another data type. For example, for an integer value x:

(float)x
static_cast<float>(x)

Operator Precedency and Associativity

When there are multiple operators in a single expression, operator precedency and associativity decide in which order and which part of expression are calculate. Precedency tells which part of expression should be calculate first and associativity tells which direction to solve when same precedency operators are in expression.

Operator Precedence

Operator precedence says which operation is calculate first in the expression when expression have different precedency operators. For example:

3 * 2 + 8;

Will be evaluated as:
(3 * 2) + 8 = 14

It is because multiplication (*) have higher precedency then addition (+).

Operator Associativity

Operator associativity says if expression have more than one operator with same precedence then calculation happen in right to left or left to right.

50 / 25 * 2 = 1

Will be evaluated as:
(50 / 25) * 2

Operators in C++

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