[PPT] - CSCI 144 - Introduction to Computer Science Instructor: John PowerPoint Presentation

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CSCI 144 - Introduction to Computer Science

Instructor: John Goettsche Computer Science Department Pacific Lutheran University Spring 20018

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Reading questions

Simple website: http://cs.plu.edu/~caora/
Enter your session number, and select

question number, also put your epass id.

Email me your suggestions for extra points

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Q1. Which of the following are

valid println statements?

A. System.out.println + "Hello World";
B. System.out.println("Have a nice dya");
C. out.System.println(value);
D. println.out(Programming is great fun);
E. None of the above.

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Q2. Which of the following is

NOT a primitive data type in Java?

A. int
B. float
C. String
D. short
E. char

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Q3. Given the following declarations, which of

the assignment statements below are NOT legal? int x; double y;

A. x = 5 / 2;
B. y = 5 / 2;
C. x = 5 / 2.0;
D. y = 5 / 2.0;
E. All of the above statements are legal.

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Correct Answers

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Q1. Which of the following are

valid println statements?

A. System.out.println + "Hello World";

B System.out.println("Have a nice dya");

C. out.System.println(value);
D. println.out(Programming is great fun);
E. None of the above.

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Q2. Which of the following is

NOT a primitive data type in Java?

A. abstract
B. float
C. String
D. short
E. char

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Q3. Given the following declarations, which of the

assignment statements below are NOT legal? int x; double y;

A. x = 5 / 2;
B. y = 5 / 2;
C. x = 5 / 2.0;
D. y = 5 / 2.0;
E. All of the above statements are legal.

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Variables, Assignment & Types

revised 09/09/2016

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“play computer”

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// calculates pounds of C02 emitted by a gasoline powered automobile public class CO2Calculator { public static void main(String[] args) { int milesDriven = 360; double mpg = 24.5; double gallonsUsed, co2Used; double emissionsFactor = 19.6; // calculate gallons of fuel used gallonsUsed = milesDriven/mpg; // calculate and display pounds of C02 emitted co2Used = gallonsUsed * emissionsFactor; System.out.println("You used " + co2Used + " pounds of C02”); } }

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Variables

int total; int count, temp, result;

data type variable name

0x000 0x001 0x002 0x003 0x004 0x005 0x006 0x007

memory ? ? ? ?

int total= 10;

10

int count = 5, temp = 2, result;

5 2

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Assignment

total = 55;

assignment operator expression on the right is evaluated value that was in total is overwritten variable must be consistent with the variable's declared type 0x000 0x001 0x002 0x003 0x004 0x005 0x006 0x007

memory

10

int total = 10;

result is stored in the variable on the left 55 10 55 variable can only hold

ne value at a time

55.5

total = 55.5;

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public class Geometry { // Prints the number of sides of several geometric shapes. public static void main (String[] args) { int sides = 7; // declaration with initialization System.out.println ("A heptagon has " + sides + " sides."); sides = 10; // assignment statement System.out.println ("A decagon has " + sides + " sides."); sides = 12; System.out.println ("A dodecagon has " + sides + " sides."); } }

memory

utput

A heptagon has 7 sides. A decagon has 10 sides.

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Constants

final int MIN_HEIGHT = 69; MIN_HEIGHT memory

69

MIN_HEIGHT = 72;

Uses for constants:

– give names to otherwise unclear literal values – facilitate updates of values used throughout a program – prevent inadvertent attempts to change a value

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Primitive Data Types

8 primitive data types in Java

byte short int long

integers

float double

floating point numbers

char

characters

boolean

Boolean values

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Numeric Primitive Data

Type byte short int long float double St Storage ge 8 bits 16 bits 32 bits 64 bits 32 bits 64 bits Min Value

128

128

32,768

68

2,147,

7,48 483,6 ,648 < < -9 x 1018

18

+/ +/- 3.4 x 1038

38 with 7 s

signific ifican ant t digits +/ +/- 1.7 x 10308

308 with 15 signific

fican ant digits ts Max Value 127 127 32,767 2,147,4 ,483 83,64 647 > 9 x x 1018

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Characters

A char variable stores a single character from the Unicode

character set

A character set is an ordered list of characters, and each

character corresponds to a unique number

The Unicode character set uses sixteen bits per character,

allowing for 65,536 unique characters

It is an international character set, containing symbols and

characters from many world languages

Character literals are delimited by single quotes:

'a' 'X' '7' '$' ',' '\n'

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Boolean

A boolean value represents a true or false condition
A boolean also can be used to represent any two

states, such as a light bulb being on or off

The reserved words true and false are the only

valid values for a boolean type

boolean done = false;

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CAT: Categorization Grid

Values Integer Floating-Point 1.Current temperature in degrees Celsius 2.The population of lemmings 3.Your grade point average 4.A person's age in years 5.A person's weight in pounds 6.A person's height in meters 7.Miles traveled 8.Number of rainy days in the past month 9.A locker number 10.Number of seconds remaining in a game 11.The sum of a series of integers 12.The average of a series of integers

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CAT: Categorization Grid

Values Integer Floating-Point 1.Current temperature in degrees Celsius 2.The population of lemmings 3.Your grade point average 4.A person's age in years 5.A person's weight in pounds 6.A person's height in meters 7.Miles traveled 8.Number of rainy days in the past month 9.A locker number 10.Number of seconds remaining in a game 11.The sum of a series of integers 12.The average of a series of integers

           

PI - primitives

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Arithmetic Expressions

An expression is a combination of one
r more operands and their operators
Arithmetic expressions use the
perators:
If either or both operands associated

with an arithmetic operator are floating point, the result is a floating point

Addition + Subtraction

Multiplication

* Division / Remainder %

(no ^ operator)

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Division and Remainder

If both operands to the division operator

(/) are integers, the result is an integer (the fractional part is discarded)

The remainder operator (%) returns the

remainder after dividing the second

perand into the first

14 / 3 equals? ls? 8 / 12 equals? ls? 4 14 % 3 equals? ls? 8 % 12 equals? ls? 2 8

PI – expression eval

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Division and Remainder Practice

1. 12 / 5
2. 6 / 12
3. 5 / 2
4. 5 / 2.0
5. 11 % 3
6. 8 % 4
7. 29 % 5
8. 3 % 7

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Operator Precedence

Multiplication, division, and remainder are evaluated

prior to addition, subtraction, and string concatenation

Examples:

a + b + c + d + e 1 4 3 2 a + b * c - d / e 3 2 4 1 a / (b + c) - d % e 2 3 4 1 a / (b * (c + (d - e))) 4 1 2 3

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Expression Practice

Indicate the order in which the operators will be evaluated by writing a number beneath each operator:

1. a – b + c – d
2. a + b * c / d
3. a * b / c * d
4. a - (b – ( c – d) – e)
5. a + (b – c) * d – e
6. (a + b * c) + (d + e) % f

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Online practices

Go to website: http://cs.plu.edu/~caora/

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Q4. You see the following expression in some code that

successfully compiles: n = 100000; What type can n not be?

A. int
B. short
C. float
D. double
E. long

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Q4*. You see the following expression in some code that successfully compiles: n = 100000; What type can n not be?

A. int
B. short
C. float
D. double
E. long

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Q6. You see the following expression in some code that

successfully compiles: n = -15; What type can n not be?

A. int
B. double
C. short
D. char
E. long

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Q6*. You see the following expression in some code that successfully compiles: n = -15; What type can n not be?

A. int
B. double
C. short
D. char
E. long

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Q8. Given the code

int x = 27; int y = 12; What is the value of the expression x/y?

A.2
B. 2.25
C. 3
D. 3.0
E. None of the above.

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Q8*. Given the code int x = 27; int y = 12; What is the value of the expression x/y?

A.2
B. 2.25
C. 3
D. 3.0
E. None of the above.

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Q10. Given the code

int x = 27; int y = 12; What is the value of the expression x%y?

A. 2
B. 2.25
C. 3
D. 3.0
E. None of the above.

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Q10*. Given the code int x = 27; int y = 12; What is the value of the expression x%y?

A. 2
B. 2.25
C. 3
D. 3.0
E. None of the above.

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practice…

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Carbon footprint for air travel

5000 2500 800 250 extended long medium short

Source: http://www.climatecrisis.net/takeaction/carboncalculator/

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Carbon footprint for air travel

5000 2500 800 250 extended long medium short

Emissions factors

.64 lbs/mile .45 lbs/mile .39 lbs/mile .39 lbs/mile Source: http://www.climatecrisis.net/takeaction/carboncalculator/

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Together we will complete a Java program to calculate carbon emissions for short and medium flights Algorithm assign the number of short flights taken (numShort) assign the number of medium flights (numMedium) calculate total carbon emissions (totalEmissions)

numShort * shortDist * shortEmission + numMedium * medDist * medEmission

display total carbon emissions

Practice Exercise

download CO2AirTravel.java from the csci144 blog page http://www.cs.plu.edu/144 -> Class blog Section 1&2

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