Skip to content
Skip to main content

About this free course

Download this course

Share this free course

Data and processes in computing
Data and processes in computing

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Exercises on Section 3

Exercise 7

Each of (a)–(c) is a member of one of the sets given in (i)–(iii). Say which item comes from which set.

Sets: (i) SetOfSeqOfChar. (ii) SeqOfSetOfChar. (iii) SeqOfSeqOfChar.

  • (a) {“error1”, “error2”, “error3”}.

  • (b) [“error1”, “error2”, “error3”].

  • (c) [{‘e’,‘1’}, {‘T’}, {‘q’,‘w’,‘e’,‘r’,‘t’,‘y’}].



  • (a) This is a set, as shown by the outer curly brackets. Each member of this set is a string, that is, a sequence of characters. So (a) is a set of sequences of characters. It is a member of SetOfSeqOfChar.

  • (b) This is a sequence, as shown by the outer square brackets. It is a sequence of strings. So (b) is a sequence of sequences of characters. It comes from SeqOfSeqOfChar.

  • (c) This is again a sequence. Each member of this sequence is a set of characters. So (c) comes from SeqOfSetOfChar.

Exercise 8

Let Mix be the disjoint union Int Char. What is the length of the following sequence from SeqOfMix?

[555, ‘5’, ‘5’, ‘5’, 11, 1].



There are six items in the sequence [555,‘5’,‘5’,‘5’,11,1] (three integers and three characters), so the length of this sequence is 6.