Strings
Our original definition of a string was "A sequence of characters enclosed in
quotation marks; Ruby's representation of text." Strings and arrays have much in
common. Both are sequences that can be accessed and manipulated, often using the
same methods. It's useful to think of strings as arrays of one-character
strings, though ["c", "a", "t"] and "cat" are not technically equivalent.
Access, Assignment, and Concatenation
Like arrays, strings use the bracket method for access. Each character
corresponds to an index. Strings are zero-indexed like arrays. The only
difference between array access and string access is that the first and last
methods are unavailable to strings.
words_to_the_third = "Words, words, words."
words_to_the_third[0] #=> "W"
words_to_the_third[-1] #=> "."
words_to_the_third[2..10] #=> "rds, word"
words_to_the_third[2..-1] #=> "rds, words, words."
words_to_the_third[2..(words_to_the_third.length - 1)] #=> "rds, words, words."
words_to_the_third[99] #=> nil
Try running the code. (Click the run button.)
String assignment uses the same syntax as array assignment.
scary_word = "palindromic"
scary_word[0] = "a"
scary_word #=> "aalindromic"
scary_word[1..6] = "ibohph"
scary_word[-3..-1] = "bia"
scary_word #=> "aibohphobia"
Try running the code. (Click the run button.)
Note: b = a[3] and c = a[4..-1] should be b = aa[3] and c = aa[4..-1]
As you'd probably guess, one concatenates strings similarly to arrays. The only
difference is that the shovel operator (<<) also concatenates strings. While
shoveling one array into another causes nestedness, strings cannot be nested; <<
therefore merely concatenates strings.
# concatenation with + does not modify the original array
broken_half_one = "we belong"
broken_half_two = "together"
broken_half_one + " " + broken_half_two #=> "we belong together"
broken_half_one #=> "we belong"
# use the assignment operator to modify broken_half_one
broken_half_one = broken_half_one + " "
broken_half_one = broken_half_one + broken_half_two
broken_half_one #=> "we belong together"
# concatenation with concat or << modifies the original array
broken_half_one = "we belong"
broken_half_two = "together"
broken_half_one.concat(" ")
broken_half_one #=> "we belong "
broken_half_one << "together"
broken_half_one #=> "we belong together"
Try running the code. (Click the run button.)
It's also sometimes useful to multiply strings using the * operator, which
functions as you'd expect:
"echo" * 4 #=> "echoechoechoecho"