How to check if a string contains a specific substring in Ruby?

In Ruby, you can check if a string contains a specific substring using various methods and techniques. Here are some common approaches:

1. `include?` Method: You can use the `include?` method to check if a string contains a specific substring. This method returns `true` if the substring is found within the string and `false` otherwise.

```ruby

   text = "Hello, world!"

   substring = "world"




   if text.include?(substring)

     puts "The text contains the substring."

   else

     puts "The text does not contain the substring."

   end

   ```

   In this example, the code will output “The text contains the substring.”

2. Regular Expressions: Ruby supports regular expressions for more complex pattern matching. You can use the `=~` operator with a regular expression to check for the presence of a substring.

  ```ruby

   text = "Hello, world!"

   substring = /world/




   if text =~ substring

     puts "The text contains the substring."

   else

     puts "The text does not contain the substring."

   end

   ```

   This code will also output “The text contains the substring.”

3. `index` Method: The `index` method can be used to find the starting position of a substring within a string. If the substring is not found, it returns `nil`.

 ```ruby

   text = "Hello, world!"

   substring = "world"




   if text.index(substring)

     puts "The text contains the substring."

   else

     puts "The text does not contain the substring."

   end

   ```

   This code will yield “The text contains the substring.”

These methods provide different ways to check for the presence of a substring in a string, allowing you to choose the one that best suits your specific use case and coding style. Whether you need a simple check or more advanced pattern matching, Ruby provides the tools to accomplish the task efficiently.