Operators in C / C++
Operators are the foundation of any programming language. We can define operators as symbols that help us to perform specific mathematical and logical computations on operands. In other words, we can say that an operator operates the operands. For example, ‘+’ is an operator used for addition, as shown below:
c = a + b;
Here, ‘+’ is the operator known as the addition operator and ‘a’ and ‘b’ are operands. The addition operator tells the compiler to add both of the operands ‘a’ and ‘b’.
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The functionality of the C/C++ programming language is incomplete without the use of operators.
C/C++ has many built-in operators and can be classified into 6 types:
- Arithmetic Operators
- Relational Operators
- Logical Operators
- Bitwise Operators
- Assignment Operators
- Other Operators
The above operators have been discussed in detail:
1. Arithmetic Operators:
These operators are used to perform arithmetic/mathematical operations on operands. Examples: (+, -, *, /, %,++,–). Arithmetic operators are of two types:
a) Unary Operators: Operators that operate or work with a single operand are unary operators. For example: Increment(++) and Decrement(–) Operators
int val = 5; ++val; // 6
b) Binary Operators: Operators that operate or work with two operands are binary operators. For example: Addition(+), Subtraction(-), multiplication(*), Division(/) operators
int a = 7; int b = 2; cout<<a+b; // 9
2. Relational Operators:
These are used for the comparison of the values of two operands. For example, checking if one operand is equal to the other operand or not, an operand is greater than the other operand or not, etc. Some of the relational operators are (==, >= , <= )(See this article for more reference).
int a = 3; int b = 5; a < b; // operator to check if a is smaller than b
3. Logical Operators:
Logical Operators are used to combining two or more conditions/constraints or to complement the evaluation of the original condition in consideration. The result of the operation of a logical operator is a Boolean value either true or false.
For example, the logical AND represented as ‘&&’ operator in C or C++ returns true when both the conditions under consideration are satisfied. Otherwise, it returns false. Therefore, a && b returns true when both a and b are true (i.e. non-zero)(See this article for more reference).
(4 != 5) && (4 < 5); // true
4. Bitwise Operators:
The Bitwise 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. The mathematical operations such as addition, subtraction, multiplication, etc. can be performed at bit-level for faster processing. For example, the bitwise AND represented as & operator in C or C++ takes two numbers as operands and does AND on every bit of two numbers. The result of AND is 1 only if both bits are 1. (See this article for more reference).
int a = 5, b = 9; // a = 5(00000101), b = 9(00001001) cout << (a ^ b); // 00001100 cout <<(~a); // 11111010
5. Assignment Operators:
Assignment operators are used to assigning 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.
Different types of assignment operators are shown below:
a. “=”: This is the simplest assignment operator. This operator is used to assign the value on the right to the variable on the left.
a = 10; b = 20; ch = 'y';
b. “+=”: This operator is combination of ‘+’ and ‘=’ operators. This operator first adds the current value of the variable on left to the value on the right and then assigns the result to the variable on the left.
(a += b) can be written as (a = a + b) If initially value stored in a is 5. Then (a += 6) = 11.
c. “-=”: This operator is a combination of ‘-‘ and ‘=’ operators. This operator first subtracts the value on the right from the current value of the variable on left and then assigns the result to the variable on the left.
(a -= b) can be written as (a = a - b) If initially value stored in a is 8. Then (a -= 6) = 2.
d. “*=”: This operator is a combination of ‘*’ and ‘=’ operators. This operator first multiplies the current value of the variable on left to the value on the right and then assigns the result to the variable on the left.
(a *= b) can be written as (a = a * b) If initially, the value stored in a is 5. Then (a *= 6) = 30.
e. “/=”: This operator is a combination of ‘/’ and ‘=’ operators. This operator first divides the current value of the variable on left by the value on the right and then assigns the result to the variable on the left.
(a /= b) can be written as (a = a / b) If initially, the value stored in a is 6. Then (a /= 2) = 3.
6. Other Operators:
Apart from the above operators, there are some other operators available in C or C++ used to perform some specific tasks. Some of them are discussed here:
a. sizeof operator:
- sizeof is much used in the C/C++ programming language.
- It is a compile-time unary operator which can be used to compute the size of its operand.
- The result of sizeof is of the unsigned integral type which is usually denoted by size_t.
- Basically, the sizeof the operator is used to compute the size of the variable.(See this article for reference)
b. Comma Operator:
- The comma operator (represented by the token) is a binary operator that evaluates its first operand and discards the result, it then evaluates the second operand and returns this value (and type).
- The comma operator has the lowest precedence of any C operator.
- Comma acts as both operator and separator. (See this article for reference)
- The conditional operator is of the form Expression1? Expression2: Expression3.
- Here, Expression1 is the condition to be evaluated. If the condition(Expression1) is True then we will execute and return the result of Expression2 otherwise if the condition(Expression1) is false then we will execute and return the result of Expression3.
- We may replace the use of if..else statements with conditional operators. (See this article for reference)
Operator Precedence Chart
The below table describes the precedence order and associativity of operators in C / C++. The precedence of the operator decreases from top to bottom.
Precedence Operator Description Associativity 1 () Parentheses (function call) left-to-right  Brackets (array subscript) . Member selection via object name -> Member selection via a pointer ++/– Postfix increment/decrement 2 ++/– 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 3 *,/,% Multiplication/division/modulus left-to-right 4 +/- Addition/subtraction left-to-right 5 << , >> Bitwise shift left, Bitwise shift right left-to-right 6 < , <= Relational less than/less than or equal to left-to-right > , >= Relational greater than/greater than or equal to left-to-right 7 == , != Relational is equal to/is not equal to left-to-right 8 & Bitwise AND left-to-right 9 ^ Bitwise exclusive OR left-to-right 10 | Bitwise inclusive OR left-to-right 11 && Logical AND left-to-right 12 || Logical OR left-to-right 13 ?: Ternary conditional right-to-left 14 = Assignment right-to-left += , -= Addition/subtraction assignment *= , /= Multiplication/division assignment %= , &= Modulus/bitwise AND assignment ^= , |= Bitwise exclusive/inclusive OR assignment <>= Bitwise shift left/right assignment 15 , expression separator left-to-right
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