Operators Precedence in C++



C++ Operators Precedence

The operator precedence determines the order in which operations are performed in an expression. Operators with higher precedence are evaluated first.

Example

Consider the following expression:

 int x = 10 + 4 * 3; 

Here, the multiplication has higher precedence than addition, so 4 * 3 is evaluated first, resulting in x = 10 + 12, which gives x = 22.

To change the order, use parentheses:

 int x = (10 + 4) * 3; 

Now 10 + 4 is evaluated first, resulting in x = 14 * 3, which gives x = 42.

C++ Operator Precedence Table

The operators are listed from top to bottom in descending order of precedence:

OperatorDescriptionExample
() [] -> .Function call, Subscript, Member accessarr[0], obj.method(), ptr->member
++ --Increment/Decrementx++, --y
! ~ - +Logical/Bitwise NOT, Unary plus/minus!flag, ~num, -value, +value
* / %Multiplication, Division, Modulusa * b, x / y, n % 2
+ -Addition, Subtractiona + b, x - y
<< >>Bitwise shiftx > 3
< <= > >=Relational operatorsa = y
== !=Equality operatorsa == b, x != y
&Bitwise ANDa & b
^Bitwise XORx ^ y
|Bitwise ORa | b
&&Logical ANDx && y
||Logical ORa || b
?:Ternary conditionalx ? y : z
= += -= *= /= %= &= ^= |= >=Assignment and compound assignmenta = b, x += y, z >>= 2
,Commax = (a, b, c)

Example of Operators Precedence

Try the following example to understand operators precedence concept available in C++. Copy and paste the following C++ program in test.cpp file and compile and run this program.

Check the simple difference with and without parenthesis. This will produce different results because (), /, * and + have different precedence. Higher precedence operators will be evaluated first −

 #include <iostream> using namespace std; main() { int a = 20; int b = 10; int c = 15; int d = 5; int e; e = (a + b) * c / d; // ( 30 * 15 ) / 5 cout << "Value of (a + b) * c / d is :" << e << endl ; e = ((a + b) * c) / d; // (30 * 15 ) / 5 cout << "Value of ((a + b) * c) / d is :" << e << endl ; e = (a + b) * (c / d); // (30) * (15/5) cout << "Value of (a + b) * (c / d) is :" << e << endl ; e = a + (b * c) / d; // 20 + (150/5) cout << "Value of a + (b * c) / d is :" << e << endl ; return 0; } 

When the above code is compiled and executed, it produces the following result −

 Value of (a + b) * c / d is :90 Value of ((a + b) * c) / d is :90 Value of (a + b) * (c / d) is :90 Value of a + (b * c) / d is :50 
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