Learning Unit 8 Programming Theory

Question 1

String Classes

Answer 1

• To Uppercase();
• To Lowercase();
• charAt();
• Substring();
• Equals ();
• Equals IgnoreCase();
• Compare To();
• Compare to IgnoreCase();
• Length();

Question 2

Equals and equals IgnoreCase Methods:

Answer 2

• Instead of operators: methods of string class are used to compare strings.
• Equals method takes the second string as a parameter
• Equals IgnoreCase is useful when: you don’t want to worry about the case the user has entered the data.

Question 3

toLowerCase and toUpperCase Methods:

Answer 3

Changes all the characters in the string to either uppercase or lowercase.

Question 4

How Strings are compared:

Answer 4

• Computer looks at each character individually .
• Computer compares Unicode values (numbers).
• If the words are not the same length, it will add the necessary spaces on the end of the shorter word before comparing words.

Question 5

Alphabetic Order using the compare to method:

Answer 5

• +ve result: 2nd value is alphabetically first
• -ve result: 1st value is alphabetically first
• Computer checks Unicode value of each characters in each word, the subtracts values to determine if the difference in values is -ve/+ve.

Question 6

How a switch statement works/When a switch statement executes:

Answer 6

1. Interpreter computes the value of expression in brackets after the word switch.
2. Looks for a case label that matches value.
3. If it finds a match: interpreter starts executing block of code at 1st statement of case label.
4. If it doesn’t find a match: interpreter starts execution at 1st statement following default.
5. If no default: interpreter skips body of switch block and carries on with the rest of the program.

Question 7

Investigation of the break statements:

Answer 7

• The absence of the break statements: statement begins executing code at 1st statement after matching case label and continues executing statements until it reaches the end of the switch block.

Question 8

Important Points on the Switch Statement/Case Statement

Answer 8

• If one value has the same output: each value must have case in front of it and a colon after.
• Break causes switch statement to be exited.
• No default and none of case labels match input value: program will jump to the line after the end of switch statement and continue.
• Relational operators may not be used: case labels and switch statements only check constant values.

Question 9

Why is the ‘shortened’ version of declaring a String allowed?

Answer 9

Strings are commonly used, it makes it easier to declare them like the other data types.

Question 10

Use of a break keyword

Answer 10

Each case clause causes interpreter to exit switch statement when it has executed the statements in that case. End of case must be specified using a break statement.