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Operator Precedence in C++ Programming

Operators in C++

In this lesson, we will learn what is the rule of Operator Precedence in C++ programming and how it works with some examples.

What is Operator Precedence

Operator Precedence in C++ programming is a rule that describe which operator is solved first in an expression. For example: * and / have same precedence and their associativity is Left to Right, so the expression 18 / 2 * 5 is treated as (18 / 2) * 5.

Let's take another example say x = 8 + 4 * 2; here value of x will be 16 and not 24 why, because * operator has a higher precedence than + operator. So 4*2 gets multiplied first and then adds into 8.

Operator Associativity means how operators of the same precedence are evaluated in an expression. Associativity can be either from left to right or right to left.

The table below shows all the operators in C++ with precedence and associativity.

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Precedence and Associativity of C++ Operators

OPERATOR DESCRIPTION ASSOCIATIVITY
( )
[ ]
. ->
++ --
Parentheses
Array Subscript
Member Selector
Post-Increment / Decrement
left to right
++ --
+ -
! ~
(type)
*
&
sizeof
Pre-Increment / Decrement
Unary plus / minus
not operator and bitwise complement
type casting
Dereference operator
Address of operator
Determine size in bytes
right to left
* / % Multiplication, Division and Modulus left to right
+ - Addition and Subtraction left to right
<< >> Bitwise leftshift and right shift left to right
< <=
> >=
relational less than / less than or equal to
relational greater than / greater than or equal to
left to right
== != Relational equal to / 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 operator right to left
=
+= -=
*= /=
%= &=
^= |=
<<= >>=
Assignment operator
Addition / subtraction assignment
Multiplication / division assignment
Modulus and bitwise assignment
Bitwise exclusive / inclusive OR assignment
Bitwise leftshift / rightshift assignment
right to left
, comma operator right to left

Please don't get confused after seeing the above table. They all are used in a different situation but not all at the same time. For solving basic equation we will consider the following operator precedence only.

  • ( ) Brackets will be solved first.
  • * / % Which ever come first from left to right in your equation.
  • + - Which ever come first from left to right in your equation.

Now let's see some examples for more understanding.

Example 1

45 % 2 + 3 * 2
45 % 2 + 3 * 2   will be solved as per operator precedence rule
1 + 3 * 2    will be solved as per operator precedence rule
1 + 6    will be solved as per operator precedence rule
7 (Answer)

Example 2

19 + (5 / 2) + 4 % 2 - 6 * 3
19 + (5 / 2) + 4 % 2 - 6 * 3     will be solved as per operator precedence rule
19 + 2 + 4 % 2 - 6 * 3     will be solved as per operator precedence rule
19 + 2 + 0 - 6 * 3     will be solved as per operator precedence rule
19 + 2 + 0 - 18     will be solved as per operator precedence rule
21 + 0 - 18     will be solved as per operator precedence rule
21 - 18     will be solved as per operator precedence rule
3 (Answer)