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mistcoversmyeyes · 2024 年2 月 3 日 12:58

Operators in C++

source@ Operators in C++ - GeeksforGeeks

An operator is a symbol that operates on a value to perform specific mathematical or logical computations. They form the foundation of any programming language. In C++, we have built-in operators to provide the required functionality.

An operator operates the operands. For example,

int c = a + b;

Here, ‘+’ is the addition operator. ‘a’ and ‘b’ are the operands that are being ‘added’.

Operators in C++ can be classified into 6 types:

Arithmetic Operators
Relational Operators
Logical Operators
Bitwise Operators
Assignment Operators
Ternary or Conditional Operators

1) Arithmetic Operators

These operators are used to perform arithmetic or mathematical operations on the operands. For example, ‘+’ is used for addition, ‘-‘ is used for subtraction ‘*’ is used for multiplication, etc.

Arithmetic Operators can be classified into 2 Types:

A) Unary Operators: These operators operate or work with a single operand. For example: Increment(++) and Decrement(–) Operators.

Name	Symbol	Description	Example
Increment Operator	++	Increases the integer value of the variable by one	int a = 5;

a–; // returns 4|

Example:

the description

Output

a++ is 10 ++a is 12 b-- is 15 --b is 13

Time Complexity: O(1)
Auxiliary Space : O(1)

Note: ++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.

B) Binary Operators: These operators operate or work with two operands. For example: Addition(+), Subtraction(-), etc.

Name	Symbol	Description	Example
Addition	+	Adds two operands	int a = 3, b = 6;

int c = a%b; // c = 2|

Note: The Modulo operator(%) operator should only be used with integers.

Example:

C++

// CPP Program to demonstrate the Binary Operators

#include <iostream>

using namespace std;

int main()

{

int a = 8, b = 3;

// Addition operator

cout << "a + b = " << (a + b) << endl;

// Subtraction operator

cout << "a - b = " << (a - b) << endl;

// Multiplication operator

cout << "a * b = " << (a * b) << endl;

// Division operator

cout << "a / b = " << (a / b) << endl;

// Modulo operator

cout << "a % b = " << (a % b) << endl;

return 0;

}

Output

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

Time Complexity: O(1)
Auxiliary Space : O(1)

2) Relational Operators

These operators are used for the comparison of the values of two operands. For example, ‘>’ checks if one operand is greater than the other operand or not, etc. The result returns a Boolean value, i.e., true or false.

Name	Symbol	Description	Example
Is Equal To	==	Checks if both operands are equal	int a = 3, b = 6;

a==b;

a>b;

a>=b;

a<b;

a<=b;

a!=b;

// returns true|

Example:

C++

// CPP Program to demonstrate the Relational Operators

#include <iostream>

using namespace std;

int main()

{

int a = 6, b = 4;

// Equal to operator

cout << "a == b is " << (a == b) << endl;

// Greater than operator

cout << "a > b is " << (a > b) << endl;

// Greater than or Equal to operator

cout << "a >= b is " << (a >= b) << endl;

// Lesser than operator

cout << "a < b is " << (a < b) << endl;

// Lesser than or Equal to operator

cout << "a <= b is " << (a <= b) << endl;

// true

cout << "a != b is " << (a != b) << endl;

return 0;

}

Output

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

Time Complexity: O(1)
Auxiliary Space : O(1)

Here, 0 denotes false and 1 denotes true. To read more about this, please refer to the article – Relational Operators.

3) Logical Operators

These 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.

Name Symbol Description Example
Logical AND && Returns true only if all the operands are true or non-zero int a = 3, b = 6;

a&&b;

// returns true
Logical OR Returns true if either of the operands is true or non-zero int a = 3, b = 6;

a b;

// returns true
Logical NOT ! Returns true if the operand is false or zero int a = 3;

!a;

// returns false

Example:

C++

// CPP Program to demonstrate the Logical Operators

#include <iostream>

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) << endl;

return 0;

}

Output

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

Time Complexity: O(1)
Auxiliary Space : O(1)

Here, 0 denotes false and 1 denotes true. To read more about this, please refer to the article – Logical Operators.

4) Bitwise Operators

These operators are used to perform bit-level operations on the operands. The operators are first converted to bit-level and then the calculation is performed on the operands. Mathematical operations such as addition, subtraction, multiplication, etc. can be performed at the bit level for faster processing.

Name	Symbol	Description	Example
Binary AND	&	Copies a bit to the evaluated result if it exists in both operands	int a = 2, b = 3;

(a & b); //returns 2|
|Binary OR|||Copies a bit to the evaluated result if it exists in any of the operand|int a = 2, b = 3;

(~b); //returns -4|

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

Example:

C++

// CPP Program to demonstrate the Bitwise Operators

#include <iostream>

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) << endl;

return 0;

}

Output

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

Time Complexity: O(1)
Auxiliary Space : O(1)

To read more about this, please refer to the article – Bitwise Operators.

5) Assignment Operators

These operators are used to assign value to a variable. The left side operand of the assignment operator is a variable and the right side operand of the assignment operator is a value. The value on the right side must be of the same data type as the variable on the left side otherwise the compiler will raise an error.

Namemultiply	Symbol	Description	Example
Assignment Operator	=	Assigns the value on the right to the variable on the left	int a = 2;

a+=b; // a = 6|
|Subtract and Assignment Operator|-=|First subtracts the value on the right from the current value of the variable on left and then assign the result to the variable on the left|int a = 2, b = 4;

a-=b; // a = -2|
|Multiply and Assignment Operator|*=|First multiplies the current value of the variable on left to the value on the right and then assign the result to the variable on the left|int a = 2, b = 4;

a /=b; // a = 2|

Example:

C++

// CPP Program to demonstrate the Assignment Operators

#include <iostream>

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) << endl;

return 0;

}

Output

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

Time Complexity: O(1)
Auxiliary Space : O(1)

6) Ternary or Conditional Operators(?

This operator returns the value based on the condition.

Expression1? Expression2: Expression3

The ternary operator ? determines the answer on the basis of the evaluation of Expression1. If it is true, then Expression2 gets evaluated and is used as the answer for the expression. If Expression1 is false, then Expression3 gets evaluated and is used as the answer for the expression.

This operator takes three operands, therefore it is known as a Ternary Operator.

Example:

C++

// CPP Program to demonstrate the Conditional Operators

#include <iostream>

using namespace std;

int main()

{

int a = 3, b = 4;

// Conditional Operator

int result = (a < b) ? b : a;

cout << "The greatest number is " << result << endl;

return 0;

}

Output

The greatest number is 4

Time Complexity: O(1)
Auxiliary Space : O(1)

7) There are some other common operators available in C++ besides the operators discussed above. Following is a list of these operators discussed in detail:

A) sizeof Operator: This unary operator is used to compute the size of its operand or variable.

sizeof(char); // returns 1

B) Comma Operator(,): This binary operator (represented by the token) is used to evaluate its first operand and discards the result, it then evaluates the second operand and returns this value (and type). It is used to combine various expressions together.

int a = 6; int b = (a+1, a-2, a+5); // b = 11

C) → Operator: This operator is used to access the variables of classes or structures.

cout<first_name;

D) Cast Operator: This unary operator is used to convert one data type into another.

float a = 11.567; int c = (int) a; // returns 11

E) Dot Operator(.): This operator is used to access members of structure variables or class objects in C++.

cout<<emp.first_name;

F) & Operator: This is a pointer operator and is used to represent the memory address of an operand.

G) * Operator: This is an Indirection Operator

C++

// CPP Program to demonstrate the & and * Operators

#include <iostream>

using namespace std;

int main()

{

int a = 6;

int * b;

int c;

// & Operator

b = &a;

// * Operator

c = *b;

cout << " a = " << a << endl;

cout << " b = " << b << endl;

cout << " c = " << c << endl;

return 0;

}

Output

a = 6 b = 0x7ffe8e8681bc c = 6

H) << Operator: It is called the insertion operator. It is used with cout to print the output.

I) >> Operator: It is called the extraction operator. It is used with cin to get the input.

int a; cin>>a; cout<<a;

Time Complexity: O(1)
Auxiliary Space : O(1)

Operator Precedence Chart

Precedence Operator Description Associativity

() Parentheses (function call) left-to-right
Brackets (array subscript)
. Member selection via object name
→ Member selection via a pointer
++/– Postfix increment/decrement
++/– Prefix increment/decrement right-to-left
+/- Unary plus/minus
!~ Logical negation/bitwise complement
(type) Cast (convert value to temporary value of type)

Dereference
& Address (of operand)
sizeof Determine size in bytes on this implementation

*,/,% Multiplication/division/modulus left-to-right
+/- Addition/subtraction left-to-right
<< , >> Bitwise shift left, Bitwise shift right left-to-right
< , <= Relational less than/less than or equal to left-to-right

, >= Relational greater than/greater than or equal to left-to-right

== , != Relational is equal to/is not equal to left-to-right
& Bitwise AND left-to-right
^ Bitwise exclusive OR left-to-right
Bitwise inclusive OR left-to-right
&& Logical AND left-to-right
Logical OR left-to-right
?: Ternary conditional right-to-left
= Assignment right-to-left
+= , -= Addition/subtraction assignment
*= , /= Multiplication/division assignment
%= , &= Modulus/bitwise AND assignment
^= , = Bitwise exclusive/inclusive OR assignment
<>= Bitwise shift left/right assignment
, expression separator left-to-right