Supplementary tasks selection statements

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Chapter 4: Selection Statements

A. Review

A.1. What do we mean “selection” in selection statements? Introduce at least three use contexts of each

kind of selection statements.

A.2. When should we use if..else.. statements instead of conditional expressions? Give an example for

an illustration.

A.3. What is a multi-way decision? Give an example with if..else.. statements and another one with

switch..case.. statements.

A.4. When should we use if..else.. statements instead of switch..case.. statements? Give an example for

an illustration.

A.5. What is the “fall-through” property of switch..case.. statements? Give an example to illustrate this

property.

B. Practice

B.1. Write selection statements that might be used in the solutions of the problems B.1.1 to B.1.15 in

Chapter 1. Remember to write variable declaration statements before the selection statements if there

is any variable in these selection statements.

B.2. For each following description, write a corresponding selection statement.

B.2.1. If the norm of any vector is zero, let the user know that it is unable to find an angle between that

vector with the other.

B.2.2. Increase the unit price by 10 if the stock level goes below 5.

B.2.3. Double the unit price if the stock level is 1. Otherwise, decrease the stock level by 1 and increase

the unit price by its half.

B.2.4. If a date is 13 and its day is Friday, inform that the day is an unlucky day. Otherwise, it is informed

as a normal day.

B.2.5. If time is morning, introduce “orange, lemon, apple, pineapple”. If time is noon, introduce

“watermelon, apple, grape, coconut, banana”. If time is evening, introduce “plum, durian, melon,

mango”. If time is night, introduce “peach, pear, avocado”.

B.2.6. If the user chooses “open a file”, the user is given a form to enter a file name. If the user chooses

“exit the program”, a prompt about saving the current status of the user is given to the user. If the user

chooses “save”, the current status of the user is saved and the program is closed. Otherwise, the current

status of the user is deleted and the program is closed.