Operator precedence and associativity are two important concepts in C language that dictate the order in which operators are evaluated in expressions.
Operator Precedence:
Operator precedence determines the order in which operators are evaluated in an expression. Operators with higher precedence are evaluated first. For example, in the expression a + b * c, multiplication (*) has higher precedence than addition (+), so b * c is evaluated first.
Here is a brief summary of operator precedence in C, from highest to lowest:
- Postfix operators:
() [] -> . ++ -- - Unary operators:
+ - ! ~ ++ -- - Multiplicative operators:
* / % - Additive operators:
+ - - Shift operators:
<< >> - Relational operators:
< <= > >= - Equality operators:
== != - Bitwise AND operator:
& - Bitwise XOR operator:
^ - Bitwise OR operator:
| - Logical AND operator:
&& - Logical OR operator:
|| - Conditional operator:
? : - Assignment operators:
= += -= *= /= %= &= ^= |= <<= >>= - Comma operator:
,
We can use parentheses to override the default precedence and explicitly specify the order of evaluation.
Operator Associativity:
Operator associativity defines the direction in which operators with the same precedence are grouped. It can be left-to-right or right-to-left.
Left-to-Right Associativity: Operators are evaluated from left to right when they have the same precedence. Most operators in C, like addition (
+), multiplication (*), and assignment (=), have left-to-right associativity.Example:
a + b + cis equivalent to(a + b) + c.Right-to-Left Associativity: Operators are evaluated from right to left when they have the same precedence. Unary operators, such as the post-increment operator (
a++), have right-to-left associativity.Example:
a++is equivalent toa = a + 1.
Understanding operator precedence and associativity is crucial for writing correct and predictable expressions in C. It helps avoid ambiguities in expressions and ensures that the code behaves as expected.
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