Numbers in

About Numbers

Crystal has a type, Number, which is the base type for all numeric types. There are two main sub-types inside the Number type: Int and Float.

Int is short for integer and represents whole numbers. Int can be both negative and positive, with no decimal point.

1.class
# => Int32

-1.class
# => Int32

Float represents numbers with a decimal point. Floats can be both negative and positive.

10.5.class
# => Float64

Converting between Int and Float

Using the 'to_i' and' to_f' methods, you can convert between Int and Float. The number is rounded down when converting from Float to Int.

1.to_f
# => 1.0

1.0.to_i
# => 1

1.9.to_i
# => 1

Arithmetic operators

You can use the basic arithmetic operators on Int and Float. The operators are +, -, *, /, and %. When using these operators, you can mix and match Int and Float.

Addition & Subtraction & Multiplication

The + operator is used for addition, the - operator is used for subtraction, and the * operator is used for multiplication.

Division

Division is used to divide numbers. The / operator is used for division. The result will always be a Float.

4 / 2
# => 2.0

4.0 / 2
# => 2.0

1 / 0
# => Infinity

-1 / 0
# => -Infinity

0 / 0
# => NaN

Integer division

Integer division is used to divide numbers and get the whole part of the result. The result will always be rounded down to an Int.

4.0 // 2
# => 2

4.5 // 2
# => 2

Modulus

Modulus is used to get the remainder of a division. The % operator is used for modulus.

5 % 2
# => 1

5.0 % 2
# => 1.0

5 % 3
# => 2

1 % 0
# Error: Unhandled exception: Division by 0 (DivisionByZeroError)

Exponentiation

Exponentiation is used to raise a number to a power. The ** operator is used for exponentiation. The result of an operation with a Float and an Int will be a Float.

2 ** 2
# => 4

2.0 ** 2
# => 4.0

Rounding

The round method takes an optional argument: the number of decimal places to round to. The default number of decimal places is 0.

1.0.round
# => 1

1.5.round
# => 2

1.234.round(2)
# => 1.23

Rounding up and down

You can also round up or down to an Int using the ceil and floor methods. The ceil method rounds up, and the floor method rounds down.

1.0.ceil
# => 1

1.2.ceil
# => 2

1.7.floor
# => 1

Priority and parentheses

Crystal allows parentheses(()), which can be used to group expressions. This is useful when you want to change the order of operations.

When using multiple arithmetic operators, the order of operations is the same as in mathematics, also known as PEMDAS. It follows the order of parentheses(()), exponents(**), multiplication(*) and division(/), and addition(+) and subtraction(-).

2 + 3 - 4 * 4
# => -11

(2 + 3 - 4) * 4
# => 4