Operator Precedence in C Programming
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.
Basic Operator Precedence
When solving arithmetic equations, follow this order:
1. Brackets ( )If brackets are there in an equation then it will be solved first.
Example:
(2 + 3) * 4 -> first do 2 + 3 -> then multiply.
These are equal in priority. Solve from left to right as they appear in an equation.
Example:
12 / 2 * 3
-> First do 12 / 2 = 6
-> Then 6 * 3 = 18
Do not do multiplication before division or vice versa — just go left to right.
3. Addition and Subtraction: +, −These also have equal priority. Solve from left to right as they appear in an equation.
Example:
10 − 3 + 2
-> First do 10 − 3 = 7
-> Then 7 + 2 = 9
Now let's see some examples for more understanding.
int x = 45 % 2 + 3 * 2; // result of x is 745 % 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)
int x = 19 + (5 / 2) + 4 % 2 - 6 * 3; // result of x is 319 + (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)
List of Operator Precedence in C
The table below shows all the operators in C with precedence and associativity.
| 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 left shift Bitwise 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 left shift / right shift assignment |
right to left |
| , | comma operator | right to left |
Test Your Knowledge
Attempt the questions in the exercise to check whether you have understood the lesson clearly.
