Ruby Ranges

What is a Range in Ruby?

In Ruby, a range is a data type that represents a sequence of values. Any data type, including numbers, characters, and even dates, can be used in the sequence. A range is characterized by two endpoints, one at the beginning and one at the end. The values at the start and finish might be inclusive or exclusive depending on the type of range being used.

How Does It Work?

Ranges are represented in Ruby by two dots .. or three dots ... between the two endpoints. The two-dot notation creates a range that includes both endpoints, while the three-dot notation creates a range that excludes the last endpoint. For example, the range 1..5 would include the values 1, 2, 3, 4, and 5, while the range 1...5 would include the values 1, 2, 3, and 4.

Example:

Here's an example of how to use ranges in Ruby:

In this example, we create two ranges, range1 and range2. We then use the include? method to check whether a value is included in the range.

Creating Ranges in Ruby

There are several ways to create ranges in Ruby. Some of them are using the .. and ... operators, the new operator, and using custom objects.

Creating a Range Using the .. Operator

The .. operator is the easiest method to generate a range in Ruby. With this operator, a range is created that includes both the provided endpoints.

For instance:

This will create a range that includes the values 1, 2, and 3. Notice that both the endpoints (1 and 3) are included here while creating the range.

Creating a Range Using the ... Operator

The ... operator is used to create a range that includes the first endpoint but excludes the last endpoint.

For example:

This will create a range that includes the values 1, 2, and 3. The first endpoint (1) is included in the range created but the last endpoint (4) is excluded from it.

Creating a Range Using New Operator

Ruby Ranges can also be created with the new operator. The start and end values of the range are the two inputs this function receives. Both the endpoints are included here for creating the new range.

For instance:

This will create a range that includes the values 1, 2, and 3. Notice that both endpoints are included in the range created.

Creating Ranges with Custom Objects

In Ruby, ranges can be created using custom objects as long as they implement the necessary methods for comparison and sequence generation. Specifically, objects used in ranges should implement the <=> operator for comparison and the succ method to determine the next object in the sequence.

Output:

In this example, we define a custom class X which defined the two methods <=> and succ. Then we use it to create a range and print them.

Types of Ranges in Ruby

There are three types of ranges in Ruby:

• Ranges as Sequences
• Ranges as Conditions
• Ranges as Intervals.

1. Ranges as Sequences

Ranges are used to express sets of values that are sequential. They are frequently used to represent a continuous sequence or iterate through a set of values. Ranges are particularly useful for operations like looping over a specific range of integers or generating a series of results.

For Example:

In the above code, the range 1..3 is iterated over using each method. This loop will output each element of the range, which is 1, 2, and 3, respectively.

2. Ranges as Conditions

Ranges as conditions are used to check whether a value falls within a certain range. They are often used in conditional statements or to validate input. If we want to check whether a number is between 1 and 5, we could create a range (1..5) and use the include? method to check whether the number is within the range.
For Example:

Output:

In this example, since 3 is a part of the range (1..5), the if statement evaluates to true and the first put statement gets printed to the console.

3. Ranges as Intervals

Periods like days, hours, minutes, or seconds are represented by ranges as intervals. When dealing with time-based computations or scheduling, they are frequently utilized. This kind of range may be used to define a time window for an event or to calculate the time between two points in time.
For Example:

In this example, the range (Time.now..Time.now + 3600) represents the interval between the current time and one hour from now.

Ranges as intervals are valuable for time-related operations, allowing us to work with specific periods and manipulate time-based data effectively.

Ruby Range Methods

Ruby provides several methods for working with ranges, including the include? method, the each method, the to_a method, and the step method.

1. include? Method

The include? method is used to determine whether a value is present inside the range.
For instance:

In this example, we create an inclusive range from 1 to 3, i.e, 1, 2, and 3, and then checks whether the value 3 is included in the range.

2. each Method

The each method is used to iterate over all the values in the range.

For Example:

This code creates a range that includes the values 1, 2 and 3, and then prints each value to the console.

3. to_a Method

A range is transformed into an array using the to_a function.

For instance:

This code creates a range that includes the values 1, 2, and 3, and then converts the range to an array.

4. step Method

The step method is used to iterate over a range with a specific step value.

For Example:

This code creates a range that includes the values 1, 2, 3, and 4, and then iterates over the range with a step value of 2, printing every other value to the console.

Examples of Ruby Ranges

Range of Integers

In this example, first, we create integer ranges. The first range uses the .. operator and so includes both endpoints. The second one does not include the last endpoint as it uses the ... operator. So when we check whether 3 is included in the range, the first range returns true while the second one return false.

Range of Characters

In this example, we create a range of characters and then check whether a character is presented in the range.

Range of Dates

In this example, we create a range of dates. Then we use the include function to check whether a date exists in the range.