Computer Basics: Hardware and Software

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Questions and Answers

What type of error is not detected during compilation or at runtime, but causes the program to produce incorrect results?

Syntax error

Runtime error

Semantic error (correct)

Logic error

What is the data type of the value 'Java is fun'?

Class/Object type (correct)

int

char

Primitive type

What is the purpose of variables in programming?

To store and hold data (correct)

To perform arithmetic operations

To control program flow

To display output

What is the most common integer type in Java?

int Signup and view all the answers

What type of error occurs when a program tries to divide a value by zero?

Runtime error Signup and view all the answers

What is the term for the value stored by a variable?

Value Signup and view all the answers

What does the compareTo method return if the strings are equal?

Zero Signup and view all the answers

What is the purpose of the equalsIgnoreCase method?

To compare strings ignoring case Signup and view all the answers

What determines the order of characters in lexicographic order?

The order of characters in the Unicode character set Signup and view all the answers

What is the purpose of the compareTo method?

To compare two strings Signup and view all the answers

What is the Unicode value of the character 'A'?

65 Signup and view all the answers

What happens when the compareTo method finds a mismatched character?

It returns the difference of their Unicode values Signup and view all the answers

What are the two types of memory in a computer?

Main memory and Auxiliary memory Signup and view all the answers

What is the term for a digit with a value of either 0 or 1?

Bit Signup and view all the answers

In Object-Oriented Programming, what is the term for actions that objects can perform?

Methods Signup and view all the answers

What is the term for a collection of 8 bits?

Byte Signup and view all the answers

What is the term for a detailed description of how to perform a task?

Algorithm Signup and view all the answers

What is the central component of a computer that executes instructions?

CPU Signup and view all the answers

What is the characteristic of the array in the Insertion Sort algorithm?

The array is partially sorted and partially unsorted Signup and view all the answers

Which of the following algorithms is the most efficient for sorting?

Quick Sort Signup and view all the answers

What is the advantage of using Binary Search over Linear Search?

Binary Search is more efficient for large arrays Signup and view all the answers

What is the purpose of the Arrays class in Java?

To provide an efficient way of sorting arrays Signup and view all the answers

What is the complexity of a worst-case Binary Search through an array of size n?

log2(n) Signup and view all the answers

What is the search method used for unsorted arrays?

Linear Search Signup and view all the answers

What is the result of the expression s1.compareTo(s2) given the strings s1 = "ABC" and s2 = "AAB"?

A positive value Signup and view all the answers

How many values can a boolean variable have in Java?

True or false Signup and view all the answers

What is the purpose of a boolean variable in a Java program?

To make programs more readable Signup and view all the answers

How can a boolean variable be assigned a value?

Using an assignment operator Signup and view all the answers

What is the purpose of nesting if-else statements in a Java program?

To handle multiple conditions Signup and view all the answers

What is the purpose of a while statement in a Java program?

To execute a block of code repeatedly while a condition is true Signup and view all the answers

Study Notes

Errors

Logic/Semantic Errors: errors not detected during compilation or runtime, causing incorrect results
Runtime Errors: errors that occur when a program runs, but with logical errors in syntax
Example: dividing by zero, causing a divide by zero error

Data Types

Primitive Types: simple, non-decomposable values (int, double, char)
Class/Object Type: complex values with data and methods (String)
Primitive Types:
- Four integer types (byte, short, int, long)
- Two floating-point types (float, double)
- One character type (char)
- One Boolean type (boolean)

Variables

Store data such as numbers and letters
Implemented as memory locations
Data stored by a variable is called its value

Operators

Logical Operators: && (and), || (or)
Example: (x && y), where x and y are boolean variables
Equality Operators: ==, !=
Example: s1.equals(s2) or s2.equals(s1) for testing equality of objects of class String
Example: s1.compareTo(s2) for comparing strings lexicographically

Computers

Consist of hardware and software
Components: input devices, output devices, processor(s), main memory, and auxiliary memory
CPU (central processing unit) or chip
Main memory: working memory used to store program and data
Auxiliary memory: hard drives, CDs, DVDs, etc.

Object-Oriented Programming (OOP)

Treats a program as a collection of objects that interact by means of actions
Objects: objects (people, trees, cars, etc.)
Actions: methods (functions of classes)
OOP Terminology:
- Objects of the same kind have the same type and are objects of the same class
- Objects of the same class have a common set of methods and data

Algorithms

Describe a means of performing an action
Example: Insertion Sort algorithm
Insertion Sort:
- Break array into sorted and unsorted portions
- Insert values from unsorted portion into sorted portion
- Search backward through sorted values to find proper position

Arrays and Searching

Linear Search: looks in order (first to last or last to first) for an item in an array
Binary Search: efficient way to search through a sorted array
Efficiency: binary search takes log2(n) steps, better than linear search

Boolean

Primitive type with two values: true and false
Boolean variables can make programs more readable
Naming Boolean Variables: choose names such as isPositive or systemsAreOk

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