C Menu

Expression Evaluation



In the C programming language, an expression is evaluated based on the operator precedence and associativity. When there are multiple operators in an expression, they are evaluated according to their precedence and associativity. The operator with higher precedence is evaluated first and the operator with the least precedence is evaluated last.

Operator Precedence

Operator precedence is used to determine the order of operators evaluated in an expression. In c programming language every operator has precedence (priority). When there is more than one operator in an expression the operator with higher precedence is evaluated first and the operator with the least precedence is evaluated last.

Operator Associativity

Operator associativity is used to determine the order of operators with equal precedence evaluated in an expression. In the c programming language, when an expression contains multiple operators with equal precedence, we use associativity to determine the order of evaluation of those operators.

Precedence Operator Operator Meaning Associativity
1 ()
[]
→
.		 function call
array reference
structure member access
structure member access		 Left to Right
2 !
~
+
-
++
--
&
*
sizeof
(type)		 negation
1's complement
Unary plus
Unary minus
increment operator
decrement operator
address of operator
pointer
returns size of a variable
type conversion		 Right to Left
3 *
/
%		 multiplication
division
remainder		 Left to Right
4 +
-		 addition
subtraction		 Left to Right
5 <<
>>		 left shift
right shift		 Left to Right
6 <
<=
>
>=		 less than
less than or equal to
greater than
greater than or equal to		 Left to Right
7 ==
!=		 equal to
not equal to		 Left to Right
8 & bitwise AND Left to Right
9 ^ bitwise EXCLUSIVE OR Left to Right
10 | bitwise OR Left to Right
11 && logical AND Left to Right
12 || logical OR Left to Right
13 ?: conditional operator Left to Right
14 =
*=
/=
%=
+=
-=
&=
^=
|=
<<=
>>=		 assignment
assign multiplication
assign division
assign remainder
assign addition
assign subtraction
assign bitwise AND
assign bitwise XOR
assign bitwise OR
assign left shift
assign right shift		 Right to Left
15 , separator Left to Right

To understand expression evaluation in c, let us consider the following simple example expression...

6*2/ (2+1 * 2/3 + 6) + 8 * (8/4)

Evaluation of expression Description of each operation
6*2/( 2+ 1 * 2 /3 +6) +8 * (8/4) An expression is given.
6*2/(2+2/3 + 6) + 8 * (8/4) 1 is multiplied by 2, giving value 2.
6*2/(2+0+6) + 8 * (8/4) 2 is divided by 3, giving value 0.
6*2/ 8+ 8 * (8/4) 2 is added to 6, giving value 8.
6*2/8 + 8 * 2 8 is divided by 4, giving value 2.
12/8 +8 * 2 6 is multiplied by 2, giving value 12.
1 + 8 * 2 12 is divided by 8, giving value 1.
1 + 16 8 is multiplied by 2, giving value 16.
17 1 is added to 16, giving value 17.
Next Topic :Type Casting