​​​​​​​​​C tutorials #11.6



Operators Precedence
Operator precedence determines the grouping of terms in an expression and decides how an expression is evaluated. Certain operators have higher precedence than others; for example, the multiplication operator has a higher precedence than the addition operator.

For example, x = 7 + 3 * 2; here, x is assigned 13, not 20 because operator * has a higher precedence than +, so it first gets multiplied with 3*2 and then adds into 7.

In the below table, operators with the highest precedence appear at the top, those with the lowest appear at the bottom.
Note -Within an expression, higher precedence operators will be evaluated first.


Postfix  () [] -> . ++ - -   (Left to right)
Unary    + - ! ~ ++ - - (type)* & sizeof (Right to left)
Multiplicative   * / %  (Left to right)
Additive   + -  (Left to right)
Shift   << >>  (Left to right)
Relational    < <= > >=   (Left to right)
Equality   == !=   (Left to right)
Bitwise  AND  &   (Left to right)
Bitwise  XOR  ^   (Left to right)
Bitwise  OR  |   (Left to right)
Logical  AND  &&   (Left to right)
Logical  OR  ||   (Left to right)
Conditional   ?:   (Right to left)
Assignment   = += -= *= /= %=>>= <<= &= ^= |=   (Right to left)
Comma   ,   (Left to right)

Example

Try the following example to understand operator precedence in C −

#include <stdio.h>

main()
{

   int a = 20;
   int b = 10;
   int c = 15;
   int d = 5;
   int e;

   e = (a + b) * c / d;      // ( 30 * 15 ) / 5
   printf("Value of (a + b) * c / d is : %d\n",  e );

   e = ((a + b) * c) / d;    // (30 * 15 ) / 5
   printf("Value of ((a + b) * c) / d is  : %d\n" ,  e );

   e = (a + b) * (c / d);   // (30) * (15/5)
   printf("Value of (a + b) * (c / d) is  : %d\n",  e );

   e = a + (b * c) / d;     //  20 + (150/5)
   printf("Value of a + (b * c) / d is  : %d\n" ,  e );

   return 0;
}

When you compile and execute the above program, 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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