Substring: Difference between revisions

=={{header|Eiffel}}==

[https://github.com/ljr1981/rosettacode_answers/blob/main/testing/rc_substring/rc_substring_test_set.e Github Test code]

[https://youtu.be/7X-ix3Z7t-o Explainer video - 2 mins]

[https://youtu.be/zuCmC4BuPFU Substring feature explainer video - 1 min]

Each task in the description is coded with one or two lines of setup and then a pair of assertions to ensure that the proper result from the substring call. Because the {STRING} class in Eiffel is high-level, it covers both 8-bit and 32-bit strings (ASC and Unicode). If one wants to specifically code for Unicode, all one really needs to do is use {STRING_32} in the space of {STRING}.

<lang eiffel>

class

RC_SUBSTRING_TEST_SET

inherit

TEST_SET_SUPPORT

feature -- Test routines

rc_substring_test

-- New test routine

note

task: "[

Display a substring:

- starting from n characters in and of m length;

- starting from n characters in, up to the end of the string;

- whole string minus the last character;

- starting from a known character within the string and of m length;

- starting from a known substring within the string and of m length.

]"

testing:

"execution/isolated",

"execution/serial"

local

str, str2: STRING

n, m: INTEGER

do

str := "abcdefgh"

m := 2

-- starting from n characters in and of m length;

n := str.index_of ('e', 1)

str2 := str.substring (n, n + m - 1)

assert_strings_equal ("start_n", "ef", str2)

assert_integers_equal ("m_length_1", 2, str2.count)

-- starting from n characters in, up to the end of the string;

str2 := str.substring (n, n + (str.count - n))

assert_strings_equal ("start_n_to_end", "efgh", str2)

assert_integers_equal ("len_1a", 4, str2.count)

-- whole string minus the last character;

str2 := str.substring (1, str.count - 1)

assert_strings_equal ("one_less_than_whole", "abcdefg", str2)

assert_integers_equal ("len_1b", 7, str2.count)

-- starting from a known character within the string and of m length;

n := str.index_of ('d', 1)

str2 := str.substring (n, n + m - 1)

assert_strings_equal ("known_char", "de", str2)

assert_integers_equal ("m_length_2", 2, str2.count)

-- starting from a known substring within the string and of m length.

n := str.substring_index ("bc", 1)

str2 := str.substring (n, n + m - 1)

assert_strings_equal ("known_substr", "bc", str2)

assert_integers_equal ("m_length_3", 2, str2.count)

end

end

</lang>