Glasgow | ITP May -25 | Mirabelle Morah | Module-Structuring-and-Testing-Data | Coursework/sprint-3

[mirabellemorah]

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Changelist

Provided answers to sprint 3

Questions

Nil

[cjyuan]

Can you explain how this expression work?

[mirabellemorah]

Lines 1-3 checks the kind of input passed in the parameter. If input type is not a number or integer (eg if it's a string) then it gives the error message that the input must be an integer.

Line 6: 'Const suffixes' is an array or ordinal suffixes
Line 7: and 'const remainder' performs a modulus operation (as we learned in previous tests) on whatever input is passed in the 'num' parameter. Then it gets the digit that remains after that division. Eg 123 % 100 = 1.23 -- therefore const remainder = 23

Lines 9-11: performs multiple things:

suffixes[(remainder - 20) % 10]
Subtracts 20 from remainder, then gets last digit and uses that last digit to assign the ordinal form
Eg:

Remainder = 23: (23-20) % 10 = [0.3] 3, so const suffix [3] = rd. There it will assign 23 as '23rd'

Then for '|| suffixes[remainder]' if an answer is undefined it simple uses the remainder with the direct array number: like

if remainder = 1: suffixes[1] = "st"
if remainder = 2: suffixes[2] = "nd"

etc.

The final fallback if both previous parts are undefined it goes back to || suffixes[0] which adds 'th' to numbers like 11th etc.

[cjyuan]

Would the code still work if we changed
(suffixes[(remainder - 20) % 10] || suffixes[remainder] || suffixes[0])
to
(suffixes[remainder] || suffixes[(remainder - 20) % 10] || suffixes[0])
(Change the order of the first two conditions)

If not, can you find a number in the range [0, 100) which the latter would fail?

---

> Eg 123 % 100 = 1.23 -- therefore const remainder = 23
  ^^^^^^^^^^^^^^^^^^^

This unusual notation makes it looks like you are treating % as a division operator.

You could just write 123 % 100 = 23 (all programmers should recognise what % operator does)

[cjyuan]

Changes look good. Well done!