warm-up: monday, february 24
DESCRIPTION
Warm-up: Monday, February 24. In outputting, what does “\n” do? In outputting, what is the difference between the System.out.print ( ) command and the Serial.out.println ( ) command? . Warm-up: Monday, February 24. In outputting, what does “\n” do? - PowerPoint PPT PresentationTRANSCRIPT
+Warm-up: Monday, February 24 In outputting, what does “\n” do?
In outputting, what is the difference between the System.out.print( ) command and the Serial.out.println( ) command?
+Warm-up: Monday, February 24 In outputting, what does “\n” do?
Goes to the next line; like hitting “enter”
In outputting, what is the difference between the System.out.print( ) command and the Serial.out.println( ) command? print( ) stays on the same line println( ) will go to the next line
+
Arithmetic OperatorsPAP Computer Science, Cycle
5
+8 Mathematical Operators Addition (+)Subtraction (-)Multiplication (*)Division (/)Modulus (%)Exponent (^) Increment (++)Decrement (--)
+Addition, Subtraction, MultiplicationThese operators work identically in
programming as in traditional math
5 + 8 1310 – 4 64 * 3 12
+Division Works differently for integers (whole
numbers) and decimals If operands are integers, the answer will be
an integer If operands are decimals, the answer will be
a decimal
11 / 2 5 11.0 / 2.0 5.5
+Modulus (%)Modulus returns the remainder from
divisionExample: 26 % 5 1 26 / 5 5
+Incrementing (++)
Increases the value of a variable by 1
Exampleint x = 5;x++;System.out.print(x) 6
+Decrementing (--)
Decreases the value of a variable by 1
Exampleint x = 5;x--;System.out.print(x) 4
+Pre- and Post-Incrementing When incrementing/decrementing, you can
put the operator before or after the variable
Exampleint x = 5; int y = 5;x++; ++y; x 6 y 6
+Pre- and Post-IncrementingExample:
int x = 5;int y = x++;
x 6 y 5Example:
int x = 5;int y = ++x;
x 6 y 6
+Order of Operations
( ) •Parenthesis
++ --
•Increment•Decrement
^ •Exponents
* / %•Multiplication•Division•Modulus
+ - •Addition•Subtraction
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6
21 – 6 + 2 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6
21 – 6 + 2 + 6
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6
21 – 6 + 2 + 615 + 8
+OOO Example
3 * 7 – 6 + 2 * 5 / 4 + 621 – 6 + 2 * 5 / 4 + 621 – 6 + 10 / 4 + 6
21 – 6 + 2 + 615 + 8
23
+Warm-up: Tuesday, Feb 25
What does the % operator return?
int x = 6;x++;
What does ‘x’ equal now?
+
Creating Variables
PAP Computer Science, Cycle 5
+Variables
Variables are place-holders for values Storage locations
They reference a single number, character, or String, and can be called by their name.
Example: X = 5 Y = X + 5;
+Declaring a Variable
Variables must be declared with two things: Data type Name
Initializing a variable (giving it a value) is NOT required when declaring a variable
+Declaring/Initializing a VariableExample 1
int x;x = 5;
Example 2int x = 5;
+Initializing a Variable
Variable name ALWAYS goes on the left
x = 5 NOT 5 = x
y = xSets y to whatever is stored in x
+Naming a VariableNames in Java must follow certain rules
Naming conventions hold true for variables, methods, classes, etc
1. Cannot be a reserved word int, float, double, char, void, public, static,
return2. Can only consist of letters, numbers, _, $3. Cannot begin with a number4. Case sensitive
X != x VAR != var Test != test
+Legal Identifiers
Variablestrnum_of_books$Amount integer3convert2fahr
+Illegal Identifiers (Names)employee salary
Spaces are not allowedHello!
! is not allowedone+two
+ is not allowed2nd
Cannot begin an identifier with a number
+Data TypesData types refer to the type of data that
will be stored in the variableLets the computer know how much
memory it needs to set aside for the variable
Data Types Int, Short, or Long (whole numbers) Float or Double (decimals) Byte (binary byte) Char (single character) Boolean (true/false)
+Int, Short, LongUsed for whole numbers
Short (16 bits of memory) -32,768 to 32,767
Int (32 bits of memory) -2,147,483,648 to 2,147,483,647
Long (64 bits of memory) -263 to 263
+Float and DoubleUsed for decimal point numbers
Float (32 bits) -3.4 x 1038 to 3.4 x 1038
6 to 7 digits of precision (decimal places)Double (64 bits)
-1.7 x 10308 to 1.7 x 10308
15 digits of precision (decimal places)
+Byte, Char, BooleanByte (8 bits)
Used for binary bytes (B11001101)
Char (16 bits) Used for characters (‘A’)
Boolean (1 bit) True or false
+ Using Variables in Codepublic class Variables
{
public static void main(String[ ] args)
{
int test1 = 90;
float test2 = 86.34;
int test3 = 23;
float sum = test1+test2+test3;
System.out.println(“Sum = “ + sum);
}
}
+Warm-up: Wednesday, Feb 26Write the code to declare a variable
named “number” that contains the number 45.46
+
Strings
PAP-Computer Science, Cycle 5
+Strings
List of multiple charactersAlso known as
Character array Character string String literal String constant
In Java, String is a special class
+String ClassAs a class, a String has certain properties
and methodsProperties
Length – how many letters in the String? Letter position
Methods compareTo startsWith endWith
+Declaring Strings
Works much the same way as declaring any other variable
Needs data type and a nameValue is optional
+Declaring a String
String name = “Ms. Alexander”;
String message = “Good luck on your test!”;
String weather = “It is sunny outside.”;
+Example Code - Stringspublic class Example
{
public static void main(String[] args)
{
int value = 56;
String str = “Your value is “;
System.out.println(str + value);
}
}