Chapter 2: Input, Processing, and Output

Question 1

Stages of “The Program Development Cycle”:

Answer 1

1. Design the Program
2. Write the Code
3. Correct Syntax Errors
4. Test the Program
5. Correct Logic Errors

Question 2

What is a SYNTAX ERROR?

Answer 2

Mistake such as: misspelled key word, missing punctuation, or incorrect use of an operator

Question 3

What is a LOGIC ERROR?

Answer 3

Mistake that does not prevent the program from running but causes it to produce incorrect results.

Question 4

What is PSEUDOCODE?

Answer 4

An informal language that has no syntax rules and is not meant to be compiled or executed.
Used by programmers to create models, or “mock-ups” of programs.

Question 5

What is a FLOWCHART?

Answer 5

Diagram that graphically depicts the steps that take place in a program

Question 6

Computer programs typically perform a 3 Step Process:

Answer 6

1. INPUT is received
2. Some PROCESS is performed on the input
3. OUTPUT is produced

Question 7

Print Function

Answer 7

Used to display output on the screen.

Question 8

Print function SYNTAX:

Answer 8

STRING/STRING LITERAL (str) must be enclosed in a pair of quote marks-

print(‘argument’)

> > > print(‘Hello World’)
Hello world

Question 9

comments

Answer 9

Notes of explanation that document lines or sections of a program.

• part of the program, but ignored by Python interpreter
• intended for people reading source code

Question 10

Variable

Answer 10

A name that references a value in the computer’s memory.

Question 11

Assignment statement

& operator

Answer 11

Used to create variable and make it reference a piece of data

 variable = expression

Question 12

print(the value stored in a variable)

Answer 12

>>> width = 10
>>> length = 5
>>> print(width)
10
>>> print(length)
5
>>> print(length, width)
10 5

Question 13

VARIABLE Naming Rules

Answer 13

1. Cannot use a Python key word
2. Cannot contain spaces
3. First character must be: a-z, A-Z, or an underscore_
4. After first char., may use: a-z, A-Z, 0-9, or underscores_
5. Upper & lower case char.’s are distinct

Question 14

camelCase naming convention

Answer 14

variableName begins with lower case letters & the first char. of the second and subsequent words written in uppercase-

camelCaseNamingConvention

Question 15

Python allows display of multiple items with one call to the print function by:

Answer 15

Separating items with a comma-

firstName = ‘Jane’
lastName = ‘Doe’
»> print(firstName, lastName)
Jane Doe

Question 16

A number written into a program’s code is called a NUMERIC LITERAL.

Because TYPES of numbers are stored and manipulated in different ways, Python uses data types to categorize values in memory-
3 data types:

Answer 16

1. int - a numeric literal written as whole number with no decimal is considered as an integer. (7, 124, -9)
2. float - a numeric literal written with a decimal is considered a float. (1.5, 5.0)
3. str - used for storing strings in memory. ( number = 3 or number = ‘three’ or number = ‘The number 3 is spelled, three’

Question 17

Variable reassignment

Answer 17

>>> number = 3
>>> print(number)
3
>>> number = ‘three’
>>> print(number)
three

Question 18

Input function

Answer 18

Programs commonly need to read input typed by the user on the keyboard.

Normally used as in an assignment statement, following the general format:
variable = input(prompt)

> > > name = input(‘Enter your name: ‘)
Enter your name: Jane
print(name)
Jane

User INPUT is returned to the program as a STRING

Question 19

To perform math operations on numeric data entered by the user with the input() you need to first, convert the data from str, to int or float:

Answer 19

> > > stringValue = input(‘How many hours did you work? ‘)
hours = int(stringValue)

Or more efficiently, use the NESTED FUNCTION -
»> hours = int(input(‘How many hours did you work? ‘))

Question 20

Write a program that asks the user to enter 3 different data types- their name (str), age (int), & income (float) and returns the user entered data as:

Here is the data you entered:
Name: Jane
Age: 25
Income: 7500.0

Answer 20

> > > name = input(‘Enter your name: ‘)
age = int(input(‘Enter your age: ‘))
income = float(input(‘Enter your income: ‘))
print(‘Here is the data you entered: ‘)
print(‘Name: ‘, name)
print(‘Age: ‘, age)
print(‘Income: ‘, income)

Question 21

What result is returned on:

> > > 3*3

> > > ‘3’ *3

Answer 21

> > > 3*3
9
‘3’ *3
333

Question 22

In the following, which are the math expression, the operands, and the operator?

> > > 12 + 2

Answer 22

math expression: 12+2

operands: 12 and 2
operator: +

Question 23

Python Math Operators

Answer 23

+ Addition
- Subtraction
* Multiplication
/ Division (gives result as a float)
// Integer Division (gives result as a whole number)
% Remainder (divides #s and gives the remainder)
** Exponent

Question 24

Operator Precedence:

Answer 24

First: operations enclosed in ( ) are performed
Next: exponents **
Then: multiplication, division, and remainder * / // % (from L to R)
Last: addition and subtraction + - (from L to R)

Question 25

average = (test1 + test2 + test3) / 3

Write a program to calculate the average from data entered by user

Answer 25

> > > test1 = float(input(‘First test score: ‘))
test2 = float(input(‘Second test score: ‘))
test3 = float(input(‘Third test score: ‘))
average = (test1 + test2 + test3 ) / 3
print(‘The average grade is:’, average)

Question 26

Operations performed on 2 int values will return the value as an int.
Operations performed on 2 float values will return the value as a float.
What will happen to operations performed on an int and a float?
»>5*2.0

Answer 26

The int value will be temporarily converted to a float and the result of the operation will be a float. The result is:
10.0

Question 27

Expressions that use operands of different data types are called__________.

Answer 27

Mixed-Type Expressions

Question 28

Python’s Escape Characters:

Answer 28

\n     advances output to the next line
\t      output skips over to the next horizontal tab position
\'      causes a ' mark to be printed
\"     causes a " to be printed 
\\     causes a \ to be printed

Question 29

Suppressing the Print( ) Ending New Line:

Answer 29

> > > print(‘One’, end =’ ‘)
print(‘Two’, end =’ ‘)
print(‘Three’)
One Two Three

> > > print(‘One’ , ‘Two’ , ‘Three’ , sep = ‘~~~’)
One~~~Two~~~Three

Question 30

Displaying Multiple Items with the + Operator:

STRING CONCATENATION

Answer 30

> > > print(‘This is ‘ + ‘one string.’)
This is one string.

> > > print(‘Enter the amount of ‘ +
‘sales for each day and ‘ +
‘press Enter.’)
Enter the amount of sales for each day and press Enter.

Question 31

When to expression returns the value:
pi = 3.1415926
How do you format the number to return:
pi = 3.14

Answer 31

> > > print(format(3.1415926, ‘.2f’))

3.14