string.rb

# Your job is to write a function which increments a string, to create a new string. If the string already ends with a number, the number should be incremented by 1. If the string does not end with a number the number 1 should be appended to the new string.

# Examples:

# foo -> foo1

# foobar23 -> foobar24

# foo0042 -> foo0043

# foo9 -> foo10

# foo099 -> foo100

# Attention: If the number has leading zeros the amount of digits should be considered.

def increment_string(input)
  if input.count("0-9") > 0
    input.sub(/\d+/, &:next)
  else
    input << "1"
  end
end

Test Passed: Value == "foo1"
Test Passed: Value == "foobar002"
Test Passed: Value == "foobar2"
Test Passed: Value == "foobar01"
Test Passed: Value == "foobar100"
Test Passed: Value == "1"
Expected: "f00bar1", instead got: "f01bar"
Expected: "f00b4r1", instead got: "f01b4r"
Test Passed: Value == "foobar001"
Test Passed: Value == "foobar1000"
Test Passed: Value == "foobar01000"
Test Passed: Value == "foobar002"
Test Passed: Value == "foobar2"
Test Passed: Value == "2"
Test Passed: Value == "010"