Accessing Characters and Substrings in ruby
A string in Ruby 1.8 is equivalent to an array of bytes or 8-bit character codes. The length or size method determines the array's length. One can get or set elements of the array simply by specifying the character number(index) within square brackets:
s = 'hello';
print s[0]
print s[s.length-1]
print s[-1]
print s[-2]
print s[-s.length]
print s[s.length]
You can also try this code with Online Ruby Compiler
Output
h
o
o # Another way of accessing the last character
l # The second-to-last character
h # Another way of accessing the first character
nil # There is no character at that index
Negative array indexes specify a 1-based position from the string's end. Also, if you try to access a character beyond the end of the string, Ruby does not throw an exception; instead, it returns nil.
When you index a single character in Ruby 1.9, you get single-character strings instead of character codes. Keep in mind that random access to characters is less efficient than access to the underlying bytes when working with multibyte strings with characters encoded using variable numbers of bytes:
s = 'hello'; # Ruby 1.9
print s[0]
print s[s.length-1]
print s[-1]
print s[-2]
You can also try this code with Online Ruby Compiler
Output
h # The first character of the string, as a string
o # The last character 'o'
o # Another way of accessing the last character
l # The second-to-last character
Also check out - Substr C++
Substrings
A substring is a group of characters contained within a larger string. Ruby does not have a substring method. We rely on ranges and expressions instead. We use two comma-separated operands for accessing the substring in ruby between the square brackets. The first operand specifies an index (which may be negative), and the second specifies a length (which must be non-negative). The result is the substring that begins at the specified index and continues for the specified number of characters:
s = "HELLO"
print s[0,2] # "HE"
print s[-1,1]
print s[0,0]
print s[0,10]
print s[s.length,1]
print s[s.length+1,1]
print s[0,-1]
Output
O # Returns a string, not the character code
“” # A zero-length substring is always empty
HELLO # Returns all the characters that are available
“” # There is an empty string immediately beyond the end
nil #It is an error to read past that
nil #Negative lengths don't make any sense
When you assign a string to a string indexed like this, the new string replaces the given substring. This is a deletion if the righthand side is an empty string, and an insertion if the lefthand side is zero-length.
s = "hello"
s[0,1] = "H" # Replace first letter with a capital letter
s[s.length,0] = " world" # Append by assigning beyond the end of the string
s[5,0] = "," # Insert a comma, without deleting anything
s[5,6] = "" # Delete with no insertion; s == "Hellod"
Check out this problem - Longest String Chain
Frequently Asked Questions
How do you access the characters in a string in Ruby?
One can access the characters in a string in Ruby simply by specifying the character number(index) within square brackets.
How do you get substrings in Ruby?
Ruby does not have a substring method. We use two comma-separated operands for accessing the substring in ruby between the square brackets. The first operand specifies an index (which may be negative), and the second specifies a length (which must be nonnegative).
How do you get the first 3 characters of a string in Ruby?
In Ruby, we use the square brackets syntax [] to access the characters of a string by passing the start index and length. To access the first 3 characters we will use the syntax[0,3]
How do you declare a string in Ruby?
one can just put the sequence of characters either in single quotes or double-quotes. Also, the user can store the string in any variable. In Ruby, we don't need to specify the variable's data type.
How do you get the first character of a string in Ruby?
To get the first character of a string, we can utilise the built-in chr method. Similarly, we can get the first character of a string using the subscript syntax [0].
Conclusion
In this article, we have extensively discussed the methods of accessing Characters and substrings in ruby programming.
We hope that this blog has helped you enhance your knowledge regarding accessing Characters and substrings in ruby programming and if you would like to learn more, check out Official Documentation and the following articles on
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