HW (1.1-1.7)

How many lines will the compiler ignore in the code below? int userAge; int currentDecade; int nextDecade; int nextMilestone; // FIXME: Get user age userAge = 29; // Testing with 29 currentDecade = userAge / 10; nextDecade = currentDecade + 1; nextMilestone = nextDecade * 10;

3

Consider the instruction: z = x + y. If x is 10 and y is 20, then z is assigned with _____.

30

The program has a total number of _____ instructions.

4

The expression wage * 40 * 50 resulted in what value?

40000

How many spaces will the compiler ignore in the code below? numToBuy = numNeeded - numInStock + 2;

6

A compiler generates the following error messages:Line 7: Missing semicolonLine 9: numItems not definedLine 10: Expected '(' 1) The programmer should start by examining line _____. 2) If the programmer corrects an error on line 7, the programmer should _____. 3) If the programmer does NOT find an error on line 7, the programmer should check line _____.

7 compile 6

Suppose a new instruction was inserted as follows:...z = x + y Add 1 more to z (new instruction)Put z to output What would the last instruction then output to the screen?

8

comment

A comment is text a programmer adds to code, to be read by humans to better understand the code but ignored by the compiler.

Compiler warnings

A compiler will sometimes report a warning, which doesn't stop the compiler from creating an executable program but indicates a possible logic error.

Storage

A disk (aka hard drive) stores files and other data, such as program files, song/movie files, or office documents. Disks are non-volatile, meaning they maintain their contents even when powered off.

logic error,

A logic error, also called a bug, is an error that occurs while a program runs.

memory

A memory is a circuit that can store 0s and 1s in each of a series of thousands of addressed locations, like a series of addressed mailboxes that each can store an envelope (the 0s and 1s).

multi-line comment

A multi-line comment starts with /* and ends with */, where all text between /* and */ is part of the comment. A multi-line comment is also known as a block comment.

Newline character

A new output line can also be produced by inserting \n, known as a newline character, within a string literal.

Input

A program gets data, perhaps from a file, keyboard, touchscreen, network, etc.

Process

A program performs computations on that data, such as adding two values like x + y.

Output

A program puts that data somewhere, such as to a file, screen, network, etc.

program

A program starts in main(), executing the statements within main's braces { }, one at a time.

algorithm

A sequence of instructions that solves a problem is called an algorithm.

single-line comment

A single-line comment starts with // and includes all the following text on that line. Single-line comments commonly appear after a statement on the same line.

assembly

Because 0s and 1s are hard to comprehend, programmers soon created programs called assemblers to automatically translate human readable instructions, such as "Mul 97, #9, 98", known as assembly language instructions, into machine instructions.

compile-time error.

Because a syntax error is detected by the compiler, a syntax error is known as a type of compile-time error.

semicolon

Each statement typically appears alone on a line and ends with a semicolon, as English sentences end with a period.

Find the syntax errors. Assume variable numDogs has been declared. 1) cout << numDogs. 2) cout << "Dogs: " numDogs; 3) cout < "Everyone wins."; 4) cout << "Hello friends! << endl; 5) cout << "Amy // Michael" << endl; 6) cout << NumDogs << endl; 7) int numCats numCats = 3; cout << numCats << endl; 8) cout >> numDogs >> endl;

Error Error Error Error No error Error Error Error

Spaces are always ignored by the compiler.

False

When a compiler says that an error exists on line 5, that line must have an error. 2) If a compiler says that an error exists on line 90, the actual error may be on line 91, 92, etc. 3) If a compiler generates a specific message like "missing semicolon", then a semicolon must be missing somewhere, though maybe from an earlier line.

False

A compiler warning by default will prevent a program from being created. 2) Generally, a programmer should not ignore warnings. 3) A compiler's default settings cause most warnings to be reported during compilation.

False True False

Input/output devices

Input/output devices: A screen (or monitor) displays items to a user. A keyboard allows a user to provide input to the computer, typically accompanied by a mouse for graphical displays.

machine instructions

Instructions represented as 0s and 1s are known as machine instructions, and a sequence of machine instructions together form an executable program (sometimes just called an executable).

Which instruction completes the program to compute a triangle's area? base = Get next input height = Get next input Assign x with base * height____ _ Put x to output

Multiply x by 1/2

Syntax errors

One kind of mistake, known as a syntax error, is to violate a programming language's rules on how symbols can be combined to create a program.

Memory

RAM (random-access memory) temporarily holds data read from storage and is designed such that any address can be accessed much faster than disk, in just a few clock ticks (see below) rather than hundreds of ticks.

Each statement ends with what symbol?

Semicolon ;

string literal

Text in double quotes " " is known as a string literal.

cout

The cout construct supports output; cout is short for characters out.

cout

The cout statements output various values. The return 0 statement ends the program (the 0 tells the operating system the program ended without error).

cin

The following statement gets an input value and puts that value into variable x: cin >> x; cin is short for characters in.

int wage

The int wage statement creates an integer variable named wage. The wage = 20 statement assigns wage with 20.

operating system

The operating system allows a user to run other programs and interfaces with the many other peripherals.

Processor

The processor runs the computer's programs, reading and executing instructions from memory, performing operations, and reading/writing data from/to memory.

program, application

The programmer-created sequence of instructions is called a program, application, or just app.

endl

The statement cout << endl starts a new output line, called a newline.

processors

To support different calculations, circuits called processors were created to process (aka execute) a list of desired calculations, with each calculation called an instruction.

compilers

To support high-level languages, programmers created compilers, which are programs that automatically translate high-level language programs into executable programs.

1) A bit can only have the value of 0 or 1. 2) Switches have gotten larger over the years. 3) A memory stores bits. 5) A processor executes instructions like Add 200, #9, 201, represented as 0s and 1s.

True False True True

Indicate which are valid code. 1) // Get user input 2) /* Get user input */ 3) /* Determine width and height, calculate volume, and return volume squared. */ 4) // Print "Hello" to the screen // 5) // Print "Hello" Then print "Goodbye" And finally return. // 6) /* * Author: Michelangelo * Date: 2014 * Address: 111 Main St, Pacific Ocean */ 7) // numKids = 2; // Typical number 8) /* numKids = 2; // Typical number numCars = 5; */ 9) /* numKids = 2; /* Typical number */ numCars = 5; */

Valid Valid Valid Valid Invalid Valid Valid Valid Invalid

Whitespace

Whitespace refers to blank spaces (space and tab characters) between items within a statement and blank lines between statements (called newlines). A compiler ignores most whitespace.

Indicate the actual output of each statement. Assume userAge is 22. 1) cout << "You are " << userAge << " years."; 2) cout << userAge << "years is good.";

You are 22 years. 22years is good.

Which instruction completes the program to compute the average of three numbers? x = Get next input y = Get next input z = Get next input _____ Put a to output

a = (x + y + z) / 3

Which statement gets an input value into variable numCars?

cin >> numCars;

Type a statement that gets an input value into variable numUsers.

cin >> numUsers;

Type a statement that outputs: Hello

cout << "Hello";

Which statement outputs: Welcome!

cout << "Welcome!";

Type a statement that starts a new output line.

cout << endl;

Which statement starts a new output line?

cout << endl;

Given variable numCars = 9, which statement outputs 9?

cout << numCars;

Type a statement that outputs the value of numUsers (a variable). End statement with a semicolon. Do not output a new line.

cout << numUsers;

The statement int wage; creates a variable named wage that is used to _____ the value 20.

hold

Would the following order of statements work the same as above? wage = 20; int wage;

no

variables

refer to data

Each cout statement outputs items to _____.

the screen

Program execution begins at main() and executes statements surrounded by which symbols?

{}