Objectives for Section 4

After studying this section you should be able to do the following.

• Recognise and use the terminology: function, signature, domain, semantics, input set, output set, precondition, postcondition.

• Suggest appropriate signatures and preconditions for functions corresponding to a variety of processes on numbers, characters and sequences, including those with more than one input and those that return a Boolean value.

• For given inputs, give the value returned by various functions described in this section, in particular: AT, PUT, SIZE, ASC, CHR, ADDLAST.