Sort the letters of string in alphabetical order: Difference between revisions

<lang eiffel>

class

SORT_STRING_LETTERS

feature -- Basic Ops

sort_string (s: STRING): STRING

-- Perform `sort_string' on `s' such that

-- each letter is in ascending alphabetical order.

note

deviation: "[

This Eiffel example deviates from the task requirement for this

Rosetta Code task in that we reuse Eiffel Base library code for

the {SORTED_TWO_WAY_LIST [G]}. We do this for two very good reasons:

1. Reuse is king. Never code what is already coded and tested.

2. The library code is readily available for examination

(i.e. the library code is not hidden and unaccessible).

Based on #1 and #2 above, examine the code in: {SORTED_TWO_WAY_LIST}.make_from_iterable

Specifically, look at the `extend' routine and the routines it calls (i.e. `search_after',

`put_left', and `back'). These routines will tell you the story of how sorting can

be coded in Eiffel. There is no need to rehash that code here.

]"

local

l_list: SORTED_TWO_WAY_LIST [CHARACTER]

do

create l_list.make_from_iterable (s) -- Add & Auto-sort string by chars

create Result.make_empty -- Create the Result STRING

⟳ c:l_list ¦ Result.append_character (c) ⟲ -- Populate it with the sorted chars

Result.adjust -- Remove the leading white space

end

end

</lang>

And the Test Code to operate it.

<lang eiffel>

class

RC_SORT_STRING_LETTERS_TEST_SET

inherit

TEST_SET_SUPPORT

feature -- Test routines

rc_sort_string_letters_test

-- Test {SORT_STRING_LETTERS}.

note

testing:

"covers/{SORT_STRING_LETTERS}",

"execution/isolated",

"execution/serial"

do

assert_strings_equal ("sorted", now_is_string, item.sort_string ("Now is the time for all good men to come to the aid of their country."))

end

feature {NONE} -- Test Support

now_is_string: STRING = "[

.Naaccddeeeeeeffghhhiiiillmmmnnooooooooorrrstttttttuwy

]"

item: SORT_STRING_LETTERS

-- An `item' for testing.

once

create Result

end

end

</lang>