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Words

Words. Characters and Strings. Character A single character inside of single quotes char letter = 'A' ; char digit = '0' ; Strings Zero or more character in double quotes String word = "hello" ; String robot = "r2d2" ; String nothing = "" ;. Why not string ?. String is a class

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Words

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  1. Words

  2. Characters and Strings • Character • A single character inside of single quotes char letter = 'A' ; char digit = '0' ; • Strings • Zero or more character in double quotes String word = "hello" ; String robot = "r2d2" ; String nothing = "" ;

  3. Why not string? • String is a class • Classes define data types • Names of classes start with capital letters • A convention, not a rule • Primitive types • Simplest data types of Java • int, boolean, char, double • Names start with small letters

  4. Odd things to do println('A' + 5) ; println("A" + 5) ; String s = "" ; for (char c = '0'; c < 'Z'; c++) { s = s + c ; } println(s) ;

  5. '5' vs 5 vs "5" • '5' is a character encoded as a number • But given from the ASCII standard • That is, '5' is 35 (in Hexadecimal) • 5 is the numbers of fingers on one hand • "5" is a String • With the single character '5'

  6. 'v' vs v • 'v' is a character • You cannot do the following 'v' = 30 ; • v is a variable name • If appropriately declared int v ; • You can v = 30 ;

  7. Conversion methods boolean • Converts zero to false • Converts non-zero to true byte char int float str • Converts to String

  8. Conversion example println(boolean(5)) ; println(float(5)) ; println(str(5)) ; println(int(5.7)) ; println(str(5.7)) ; println(int('5')) ; println(int('#')) ;

  9. Unicode and cut-and-paste char rquote = '‘' ; char lquote = '’' ; char singleQuote = '\''; String dquotes = "“”" ; char oe = 'œ' ; println(int(rquote)) ; println(int(oe)) ;

  10. class and method • In object-oriented programming • Classes have methods • ≈ functions • The operations for that data type • Retrieve information from objects • Modify objects • Methods (and fields) use “dot” operator • obj.method(arg1, arg2) • ≈ method(obj, arg1, arg2)

  11. Useful methods for s, a String s.length() • Number of characters of s s.charAt(5) • 5th character of s (“first” is 0th) s.substring(2, 3) • Characters 2 to 4 of s • And many more

  12. Printing on the screen • Create a font in Processing environment • Tools » Create Font…. • Load font in Processing code • Pfont font = loadFont("……") ; • Set font • textFont(font, size) ; • Write with font • text("……", x, y) ;

  13. Displaying Text // Step 1: Create the font using the Tool menu option // Step 2: Declare PFont variable PFont f; void setup() { size(200,200); // Step 3: Load Font f = loadFont("Albany-48.vlw“, 40); background(255); textFont(f, 16); // Step 4: Specify font fill(0); // Step 5: Specify font color // Step 6: Display Text text("Mmmmm ... Strings ..." , 10, 100); }

  14. You try it! // Step 1: Create the font using the Tool menu option // Step 2: Declare PFont variable PFont f; void setup() { size(200, 200); // Step 3: Load Font f = loadFont( “you fill this in" ); background(255); textFont(f, “you fill this in”); // Step 4: Specify font fill(0); // Step 5: Specify font color // Step 6: Display Text String message = “you fill this in" ; text (message, 10, 100); }

  15. Useful text functions textWidth("……") • Returns width in pixels of string when printed textAlign(LEFT) textAlign(RIGHT) textAlign(CENTER) • Aligns a text string textSize(n) • Sets size of font

  16. Try It Again PFont f; void setup() { size(200,200); f = loadFont("Arial-BoldMT-40.vlw"); textFont(f); fill(200); } void draw() { background(255); if(mousePressed && mouseButton == LEFT) { textAlign(LEFT); text ("LEFT", 5, height/2, width, height); } else if(mousePressed && mouseButton == RIGHT) { textAlign(RIGHT); text ("RIGHT", 5, height/2, width, height); } }

  17. Lab • Load an image of a dog and font into your project • Write a Processing program to display the dog along with its name • If you have time, animate your dog

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