Operator precedence and associativity

Operator precedence and associativity

Q) Explain operator presidency and associativity.

Operator Precedence of an operator:

• In an expression when there is more the one operator involved, the evaluation of them is done based on their priority.
• In C, every operator has its own priority (importance) this priority is known as the precedence of the operator.
• This operator having more precedence will be evaluated first and the remaining will be evaluated later. Consider the following expression:

a = 5 + 6 * 10 ;

• Here, the operation * will be performed first since it has higher precedence than +, later+operator will do its task and at the last =will be done.
• The priority of each operator in C is given in the following table.

Associativity of operators

• When an expression contains two or more operators of equal priority the tie between them is settled using the associativity of the operators.
• Associativity can be two types Left to Right or Right to Left.
• Left to Right associativity means that the left operand must be unambiguous. Unambiguous in what sense? It must not be involved in the evaluation of any other sub-expression. Similarly, in cases of Right to left associativity, the right operand must be unambiguous. Let us understand this with an example.

Consider the expression

a = 3 / 2 * 5 ;

• Here there is a tie between operators of the same priority, that is between / and *. This tie is settled using the associativity of / and *. But both enjoy left to Right associativity.
• The figure shows for each operator which operand is unambiguous and which is not.

• Since both / and* have L to R associativity and only / has an unambiguous left operand (a necessary condition for L to R associativity) it is performed earlier.
• After that * will be operated.

Operator Precedence Table

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