Ruby - Operators Precedence
Ruby Operators Precedence
Operator precedence (order of operations) is a collection of rules that reflect conventions about which procedures to perform first in order to evaluate a given expression.
For example, multiplication has higher precedence than addition. Thus, the expression 1 + 2 × 3 is interpreted to have the value 1 + (2 × 3) = 7, and not (1 + 2) × 3 = 9. When exponent is used in the expression, it has precedence over both addition and multiplication. Thus 3 + 52 = 28 and 3 × 52 = 75.
Operator Associativity
Operator associativity is the direction in which an expression is evaluated. For example:
x = 10 y = 20 #associativity of = operator is #Left to Right, hence x will become 20 x = y
As the associativity of = is left to right. Hence x is assigned the value of y.
Example:
The example below illustrates the operator precedence in Ruby.
#evaluates 5 * 2 first retval1 = 15 - 5 * 2 #above expression is equivalent to retval2 = 15 - (5 * 2) #forcing compiler to evaluate 15 - 5 first retval3 = (15 - 5) * 2 puts "15 - 5 * 2 = #{retval1}" puts "15 - (5 * 2) = #{retval2}" puts "(15 - 5) * 2 = #{retval3}"
The output of the above code will be:
15 - 5 * 2 = 5 15 - (5 * 2) = 5 (15 - 5) * 2 = 20
Ruby Operators Precedence Table
The following table lists the precedence and associativity of Ruby operators. Operators are listed top to bottom, in descending precedence. Operators with higher precedence are evaluated before operators with relatively lower precedence.
Precedence | Operator | Description |
---|---|---|
21 | ! | Logical NOT |
~ | Bitwise NOT | |
+a | Unary plus | |
20 | ** | Exponential operator |
19 | -a | Unary minus |
18 | * / % | Multiplication, Division, Remainder |
17 | + - | Addition, Subtraction |
16 | << >> | Bitwise left shift and right shift |
15 | & | Bitwise AND |
14 | | | Bitwise OR |
^ | Bitwise XOR | |
13 | < <= > >= | Less than, Less than or equal, Greater than, and Greater than or equal |
12 | == != | Equality and Inequality |
=== <=> | Case equality, Combined Comparison Operator | |
=~ !~ | Pattern matching operators | |
11 | && | Logical AND |
10 | || | Logical OR |
9 | .. | Range creation operators |
... | ||
8 | a?b:c | ternary (conditional) operator |
7 | modifier-rescue | Exception-handling modifier |
6 | = | Direct assignment |
+= -= *= /= %= **= | Compound assignment by sum, difference, product, quotient, remainder and exponential | |
<<= >>= | Compound assignment by Bitwise left shift and right shift | |
&= ^= |= | Compound assignment by Bitwise AND, XOR and OR | |
5 | defined? | Test variable definition and type |
4 | not | Logical NOT |
3 | and | Logical AND |
or | Logical OR | |
2 | modifier-if modifier-unless modifier-while modifier-until | Conditional and loop modifiers |
1 | { } | blocks |
❮ Ruby - Operators