While executing an arithmetic operation the precedence of the operators in C as well as other programming language matters a lot because precedence determines the grouping of terms in an expression and decides how an expression is evaluated. For instance, the expression might be having various arithmetic operators like ‘+’, ‘-‘, or ‘*’; then how to know which part of the expression gets executed first.
Priority of Operators:
Let us take a look at the precedence of commonly used operators :
here the priority goes from high(* / %) to low(=):
| Operator | Description |
| * / % | multiplication, division, modular division |
| + – | addition, subtraction |
| = | assignment |
Associativity of Operators:
When an expression contains two operators of equal priority the tie between them is settled using the associativity of the operators. Associativity can be of two types – left to right or right to left:
- Left to right associativity means that the left operand must be unambiguous i.e., it must not be involved in the evaluation of any other sub-expression.
- Likewise, in case of right to left associativity, the right operand must be ambiguous.
| Category | Operator | Associativity |
|---|---|---|
| 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 |
Consider the expression-
a = 3 / 1 * 5 ;
output: 15Here there is a tie between operators of same priority, that is between / and *. This tie is settled using the associativity of / and * since both / and * have L to R associativity and only / has unambiguous left operand ,therefore / is performed earlier.
note: also read about Variables & Constants in C & Operators in C.
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Staying up to the mark is what defines me. Hi all! I’m Rabecca Fatima a keen learner, great enthusiast, ready to take new challenges as stepping stones towards flying colors.