Exercise 2 - Numerical Data and Basic Input/Output in C++, Slides of Computer Science

A set of instructions for exercise 2 in computer science 106 or computing in engineering and science. It covers numerical data types, basic input and output in c++, and how to prepare a file for submission. An assessment quiz and goals for the exercise.

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Exercise two February 7, 2006
1
Exercise 2
Exercise 2
N
Numerical data
umerical data
types and simple input/ output
types and simple input/ output
Larry Caretto
Computer Science 106
Computing in Engineering
and Science
February 7, 2006
2
Outline
Review exercise one (can hand in this
week as late assignment)
Present assessment results
Review lecture topics for exercise two
Basic structure of simple C++ programs
Basic input and output
Instructions for preparing file to submit
List tasks for exercise two
3
Review of Exercise One
You should have learned how to use the
Visual C++ IDE to enter, compile, link,
and execute programs
You saw a sample C++ program with
A semicolon to end each statement
Braces {} to separate blocks of code
Use of cin >> and cout << for keyboard
input and screen output
4
Review Syntax Errors
Click on error message to see line
Error messages are not always clear
Error may occur on line above line
identified by error message
Single error may give multiple error
messages
Learn how to interpret error messages
during the semester
5
Assessment Results
10 students completed assessment
8 rate general computer skills above
minimal
8 students rate programming skills as
minimal or none
Two students do not have Math 150A or
higher
All students have access to a computer
at home (6 windows PC, 2 MAC 2 No
answer or answer unclear)
6
Assessment Quiz
x3dx = x4/4 + C – Three incorrect
(three more missing constant, C)
•d(e
ax)/dx = aeax Four correct
1000112= 3510 One correct; use
binary numbers to understand storage
x = 10; x = x + 5; gives x = 15 – Six
correct; shows meaning of = as
replacement of value in computing
pf3
pf4

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Exercise 2Exercise 2 – N–Numerical dataumerical data

types and simple input/ outputtypes and simple input/ output

Larry Caretto Computer Science 106

Computing in Engineering

and Science

February 7, 2006

2

Outline

  • Review exercise one (can hand in this

week as late assignment)

  • Present assessment results
  • Review lecture topics for exercise two
    • Basic structure of simple C++ programs
    • Basic input and output
  • Instructions for preparing file to submit
  • List tasks for exercise two

3

Review of Exercise One

  • You should have learned how to use the

Visual C++ IDE to enter, compile, link,

and execute programs

  • You saw a sample C++ program with
    • A semicolon to end each statement
    • Braces {} to separate blocks of code
    • Use of cin >> and cout << for keyboard input and screen output

4

Review Syntax Errors

  • Click on error message to see line
  • Error messages are not always clear
  • Error may occur on line above line

identified by error message

  • Single error may give multiple error

messages

  • Learn how to interpret error messages

during the semester

5

Assessment Results

  • 10 students completed assessment
    • 8 rate general computer skills above minimal
    • 8 students rate programming skills as minimal or none
  • Two students do not have Math 150A or

higher

  • All students have access to a computer

at home (6 windows PC, 2 MAC 2 No

answer or answer unclear)

6

Assessment Quiz

  • ∫x^3 dx = x^4 /4 + C – Three incorrect

(three more missing constant, C)

  • d(eax)/dx = ae ax^ – Four correct
    • 100011 2 = 35 10 – One correct; use

binary numbers to understand storage

  • x = 10; x = x + 5; gives x = 15 – Six

correct; shows meaning of = as

replacement of value in computing

7

Assessment Quiz

  • File definition – Four partially complete
    • a collection of information, which may be programs, data or images, stored on permanent storage (e. g., a hard drive, solid-state USB device, zip drive, CD or floppy) that can be accessed by a unique name.
  • Rounding 123.4567 to four significant

figures produces 123.5 or 1.235x10^2 –

Everyone correct!

8

Exercise Two Goals

  • Understand differences between different data types (double and int)
  • Learn results of division by zero
  • Learn effect of entering a fraction as an input for an int-data-type variable
  • Be able to write input and output
    • Multiple input values with one cin
    • Output statements with spaces and new lines

9

Basic C++ Program Structure

#include

using namespace std;

int main()

return EXIT_SUCCESS;

  • Case sensitive; ignores spaces and new lines

10

Numerical data types

  • Binary representation of numbers
  • Floating point data types (float, double

and long double)

  • Have decimal points and wide range
  • Division behaves in expected manner
  • Integer data types (int, short int, long int,

unsigned int)

  • Have narrow range
  • Integer division truncates

11

Review Output using cout

  • cout << “”; writes the string between the quotation marks to the screen
  • cout << x; writes the value of the variable, x, to the screen.
  • Can have one or more output (<<) operators in a single cout command Code Screen output

cout << “ x = “ << x; x = 2

int x = 2; cout << x; 2

cout << “Name” Name

12

Review Input using cin

  • Input prompt tells user what to input
  • Enter several variables with a single cin command - Separate entries by a space and press (the Enter key) after last entry

Type 1.4 -3.2 12.7 to set x = 1.4, y = -3.2 and z = 12.

cout << “Enter x, y, and z: “; cin >> x >> y >>z;

cout << “Enter x: “; cin >> x; Type 2.3 for x = 2.

Code Actions

19

Tasks for this Exercise

  • Copy and paste task one code from

assignment to IDE and run

  • Copy code and screen input and output

(for six cases) to submission file

  • Task two is repeat of task one with

variables changed from double to int

  • Task three provides a single input

command; run for one case only

20

Task One Code

#include using namespace std; int main() { double x, y, z; cout << “Enter a value for x: “; cin >> x; cout << “Enter a value for y: “; cin >> y; z = x / y; cout << “For x = “ << x << “ and y = “ << y << “ x / y = “ << z << “\n\n”; return EXIT_SUCCESS; }

21

Entering Powers of Ten

  • C++, like most languages, uses an “E” or

“e” to enter powers of ten

  • 3.45x10 12 is entered as 3.45e
  • -6.19x10 -32^ is entered as –6.19e-
  • We write 10 n^ as shorthand for 1x10n
  • How do you enter 10^6 and 10-6?
  • Enter 10^6 = 1x10 6 as 1e6, 1E6 or 1000000
  • Enter 10 -6^ =1x10-6^ as 1e-6, 1E-6 or 0.000001; what are 10e6 or 10E-6?
  • 10e6 = 10x10 6 = 10^7 ; 10e-6 = 10x10-6^ = 10- 22

Remaining Tasks

  • Task four looks at simple output spacing

in cout commands; one case only

  • Task five: more complicated spacing

assignment – write code giving output

exactly as shown in exercise

  • Tasks one and two show differences

between double and int as well as

effects of incorrect data

  • Due this Thursday, February 9

23

Task Five Output

Results for programming exercise 2:

Larry Caretto February 9, 2006

Input value of x = 10 Input value of y = 3 Output value of z = x / y = 3.

Press any key to continue

blank lineblank line

blank line

blank line

Two Spaces

Note alignments

decimal result