Precedence and Associativity of Operators in C
Precedence and Associativity:
On this page we will discuss about the Precedence and associativity of operators in C language.Precedence of operator comes into picture when in an expression we need to decide which operator will be executed first.Operator with higher precedence will be executed first.If the operators have same precedence in that case associativity comes into play.
Precedence and Associativity of Operators in C Language:
- Precedence of Operators – Suppose, you have multiple operators in an expression.Then which operator will be evaluated first is decided by the precedence.Operator with higher precedence will be evaluated first.
Therefore, 4+(5*6)= 34 is correct.Whereas,(4+5)*6=54 is wrong.Because precedence of (5*6) is greater so it will be evaluated first then the addition will ne performed.Hence the final answer is 34 and not 54.
- Associativity of Operators – Associativity of operators come into picture when precedence of operators are same and we need to decide which operator will be evaluated first.Associativity can be either left to right(LTR) or right to left(RTL).
Therefore,(20/4)*10=50 is correct and the 20/(4*10)=1/2 is wrong .Because the associativity of division amd multiplication is from left to right.So, division will be performed first then multiplication.
| CATEGORY | OPERATORS | Suggested Avg. Time |
|---|---|---|
| Parenthesis/brackets | ( ) [ ] -> . ++ — | Left to Right |
| Unary | ! ~ ++ — + – * & (type) sizeof | Right to Left |
| Multiplicative | * / % | Left to Right |
| Additive | + – | Left to Right |
| Bitwise Shift | << >> | Left to Right |
| Relational | < <= > >= | Left to Right |
| Equality | == != | Left to Right |
| Bitwise AND | & | Left to Right |
| Bitwise XOR | ^ | Left to Right |
Lets see an example:
#include<stdio.h>
int prep ()
{
printf ("Prep");
return 1;
}
int insta ()
{
printf ("Insta");
return 1;
}
int main ()
{
int p;
p = prep () + insta ();
printf ("%d", p);
return 0;
}
Output:
PrepInsta2
Which function is called first? prep() or inst()?
Well according to above output prep( ) is called first but it is not defined whether prep( ) will be called first or whether insta( ) will be called.Behaviour is undefined and output is compiler dependent.
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