Ruby, you can iterate over a string in various ways depending on whether you want to iterate by characters, bytes, or specific delimiters (like words or lines). Here are the common methods for iterating over strings:

1. Iterating by Characters:

You can iterate over each character in the string using the each_char method

str = "hello"
str.each_char do |char|
  puts char
end

Output

h
e
l
l
o

Alternatively, you can use chars, which returns an array of the characters, and then iterate using each

str.chars.each do |char|
  puts char
end

2. Iterating by Bytes:

If you need to iterate over the byte values of the string (especially useful in encoding situations), you can use the each_byte method.

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str = "hello"
str.each_byte do |byte|
  puts byte
end

Output:

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104
101
108
108
111

(These numbers represent the ASCII values of the characters.)

3. Iterating by Words:

You can split a string into words (usually by spaces) using split, and then iterate over the array of words.

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str = "hello world"
str.split.each do |word|
  puts word
end

Output:

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hello
world

4. Iterating by Lines:

If you have a multiline string, you can iterate over each line using the each_line method.

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str = "hello\nworld"
str.each_line do |line|
  puts line
end

Output:

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hello
world

You can also customize the line separator:

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str.each_line(",") do |line|
  puts line
end

5. Using each_with_index:

You can combine the iteration methods with each_with_index to keep track of the index while iterating. This works for characters, words, lines, etc.

Iterating by characters with index:

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str = "hello"
str.each_char.with_index do |char, idx|
  puts "#{idx}: #{char}"
end

Output:

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0: h
1: e
2: l
3: l
4: o

6. Iterating over Regex Matches:

You can use the scan method to iterate over portions of a string that match a pattern (using a regular expression).

ruby

str = "hello 123 world 456"
str.scan(/\d+/) do |match|
  puts match
end

Output:

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123
456

Summary of Methods:

• each_char: Iterates over each character.
• each_byte: Iterates over each byte of the string.
• each_line: Iterates over each line.
• split + each: Iterates over words by splitting the string.
• scan: Iterates over regex matches.
• each_with_index: Allows tracking the index during iteration.

These methods provide a lot of flexibility when you need to process strings in Ruby!