CST112 Looping Statements Page 1

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1 CST112 Looping Statements Page Processing: Looping Statements CST112 Algorithms Procedure for solving problem: 1. Actions to be executed 2. Order in which actions are executed order of elements of an algorithm are very important Even if order appears insignificant, errors can have far-reaching results Research of Bohm and Jacopini y proposed that all programs can be written in terms of three control structures: type of instructions that specify order in which statements in a program is executed 1. Sequence structure step by step in order 2. Selection (decision or conditional) structure 3. Repetition (iteration or loop) structure repeating blocks of statements Iteration (Loop) Statements Provides repeated execution of a block of statements loop continues: 1. A specified number of times (counter-controlled) or 2. While a condition is met (sentinel-controlled) Also called repetition or structure Meaning loop condition is True Iteration (Loop) Pattern One or more statements in a block are executed repeatedly Loop continues certain condition is true 6 7 (Anor rectangle?) Set ranm fill color; Set size 10 pixels smaller; Draw rectangle; for Loop Implements a loop by counting a specific number of iterations (repetitions) Counter-controlled looping Appropriate when exact number of loop repetitions is known for (initialize; booleanexpression; increment) Statement(s) to be repeated; for Loop Example (three expressions in parenses):

2 129 CST112 Looping Statements Page for ( = 0; <= 9; = + initialize component ( = 0) Value signed to a counter variable when loop is first encountered in program booleanexpression component ( <= 9) Strings Relation condition which is tested to determine if loop should be entered again A string increment is a sequence component of characters ( = + Strings Indicates are always by what defined value inside counter uble changes quotes at ("abc") beginning of each subsequent Alternately loop characters (type char) are always defined inside single quotes ('a') and Strings may only contain a single character Strings A string is a sequence of characters Strings cls are String always includes defined methods inside uble for: quotes ("abc") Alternately Examining individual characters characters (type char) within are always stringsdefined inside single quotes ('a') and Comparing may only contain stringsa single character Strings Searching strings Extracting cls String parts includes of strings methods for: Examining Converting individual an entire string characters to upperce within strings or lowerce Comparing Etc. strings Searching text() Function strings Draws Extracting data parts to of screen strings Converting data may an be entire text, string a char, to upperce an int or a or float lowerce Displays Etc. information specified in first parameter on screen in position specified text() by Function additional two parameters By default text displays starting from and n to right of positions Draws data to screen coordinates data may be text, a char, an int or a float fill() function controls color of text (default always is white) Displays information specified in first parameter on screen in position specified text() by Function additional two parameters By Format: default text displays starting from and n to right of positions coordinates text(data, xcoordinate, ycoordinate); Examples: fill() function controls color of text (default always is white) text("hello", text() Function mousex, mousey); text(, 100, 100); Text.pde text(data, xcoordinate, ycoordinate); Examples: Loops1a.pde text("hello", mousex, mousey); Loops1a.pde text(, 100, 100); Text.pde Relationship of draw() and mousepressed() functions Loops1a.pde A draw() function is needed so output from mousepressed() function will be visible Loops1a.pde This is true even if draw() is empty; orwise re will be no output to Processing output winw Relationship of draw() and mousepressed() functions Assignment A draw() function Operators is needed so output from mousepressed() function will be visible Also known op equals This Assigns is true an even d if draw() value to is empty; a variable orwise re will be no output to Processing output Operator winw Example Explanation Assignment += Operators += = + Also known op 17; equals = - 17; Assigns *= an d *= 8; value = to a * variable 8; /= /= 5; = / 5;

3 29 Loops1b.pde Also /= known /= op 5; equals = / 5; CST112 Looping Statements Page 3 Assigns an d value to a variable Loops1b.pde Operators Operator Example Explanation Loops1b.pde += += variables = + values by adding (increment operator) or subtracting (decrement operator) value of 1 to (or from) 17; = - 17; Operator Operator Operators Example Example Explanation Explanation *= *= 8; = * 8; += ++ /= ++; /= += 5; = variables = + / 5; + values (post) by adding (increment operator) or subtracting (decrement ++ ++; operator) 17; value = of to 17; (pre) (or from) Loops1b.pde Operator *= -- --; *= 8; Example = = - * 8; (post) Explanation Loops1b.pde ++ /= -- ++; --; /= 5; = = - + / 5; (pre) (post) ++ ++; = + (pre) Operators Operators -- --; = - (post) If operator is a prefix, variables value is values returned by adding after it is (increment increed operator) or decreed: -- --; = - (pre) or subtracting (decrement When operator) variable value = 5: of 1 to (or from) Operator newvar Operators = ++; Example // newvar will be Explanation 6 If ++ operator ++; is a prefix, suffix, = value + is returned (post) before: after it is increed or decreed: When ++ ++; variable = = 5: + (pre) -- newvar --; = ++; ++; = // newvar - (post) will be 65 If Final -- operator value --; of is a suffix, in both = ces value - will (pre) is returned be 6 before: When variable = 5: Loops1c.pde Operators newvar = ++; // newvar will be 5 Loops1c.pde If Final operator value of is a prefix, in both ces value will is returned be 6 after it is increed or decreed: When variable = 5: Loops1c.pde Loops1d.pde newvar = ++; // newvar will be 6 Loops1c.pde Loops1d.pde If operator is a suffix, value is returned before: When variable = 5: Loops1d.pde Variable Scope newvar = ++; // newvar will be 5 Loops1d.pde Variables are recognized in Final value of in both ces block in will be which y are declared 6 Including loop and conditional blocks Loops1c.pde Variable And all subordinate Scope blocks Loops1c.pde Variables If a variable are is recognized declared before in block first in function which y (i.e. are before declared setup() function) or outside Including of any loop function, and conditional that variable blocks h global scope Loops1d.pde And It all is recognized subordinate inside blocks every function in application Loops1d.pde Variable If a variable Scope is declared before first function (i.e. before setup() function) or outside of any function, that variable h global scope Variable In following It is recognized Scope example, variable inside every function only in application is accessible inside mousepressed() function Variables are recognized in block in which y are declared Variable It would Scope not be accessible in any or function: Including loop and conditional blocks In void mousepressed() following example, variable only is accessible inside mousepressed() And all subordinate blocks function If a variable is declared before first function (i.e. before setup() function) or It would not be accessible in any or function: outside int ; of any function, that variable h global scope void mousepressed() It is recognized inside every function in application for ( = 0; < 10; ++) Variable int ; Scope In println(); following example, variable only is accessible inside mousepressed() function for ( = 0; < 10; ++) It would not be accessible in any or function: void mousepressed() println(); Loops1e.pde Loops1e.pde int ; Loops1e.pde Variable Scope 3) for ( = 0; < 10; ++) Loops1e.pde In following example, variable only is accessible inside for block: for (int println(); = 0; < 10; ++) Variable Scope 3) In following example, variable only is accessible inside for block: println(); for (int = 0; < 10; ++) Loops1e.pde println(); Loops1e.pde println(); lt statement would result in a compile error

4 Filename: Create an output Loops3.pde winw 400 by 400 pixels In mousepressed() function draw 1000 circles with diameter of 20 pixels at ranm Create an output winw 400 by 400 pixels locations In mousepressed() function draw 1000 circles with diameter of 20 pixels at ranm RGB colors for each individual circle are ranm values between 0 and 255 locations transparency for each individual circle is a ranm value between 100 and 255 RGB colors for each individual circle are ranm values between 0 and 255 Ere output winw at each mousepressed() click to draw 1000 new circles transparency for each individual circle is a ranm value between 100 and 255 LoopsMiniQuiz1.pde Ere println(); output winw at each mousepressed() click to draw 1000 new circles LoopsMiniQuiz1.pde println(); LoopsMiniQuiz1.pde lt statement would result in a compile error Continues Loop to repeat a loop long a controlling condition is true (pre-test) variable controlling condition is d by logic within loop Continues to repeat a loop long a controlling condition is true (pre-test) Exact number of loops is usually unknown variable controlling condition is d by logic within loop Exact number of loops is usually unknown Loop Loop int = 600; ( > 0) int = 600; ( > 0) rect(width / 2, width / 2,, ); 10; rect(width / 2, width / 2,, ); 10; Loop CST112 Looping Statements Page Remember Loop if Format Remember Format of if if statement: Format if (booleanexpression) Format of if statement: if (booleanexpression) Statement(s) to be executed if booleanexpression is true; Statement(s) to be executed if booleanexpression is true; Format of statement: Format of statement: Comparing for and Comparing for example: for and for ( = <= 10; ++) for example: for ( = <= 10; ++) println(); println(); example : = // Initialize example : ( <= 10) // Boolean test = // Initialize ( <= 10) // Boolean test println(); ++; // Increment println(); ++; // Increment Loops4.pde Loops4.pde

5 56 Loops4.pde CST112 Looping Statements Page Loops4.pde Loop Loops4.pde Continues to repeat a loop long a controlling condition is true Performs test at conclusion of execution of each loop (post-test) Loops5.pde ++; // Increment Loops4.pde Statement(s) Loop to be repeated long booleanexpression is true; Continues to repeat a loop long a controlling condition is true Performs ; test at conclusion of execution of each loop (post-test) Loop rect(mysize (booleanexpression); / 2, mysize / 2,, ); 10; Loop ( > 0); A loop always executes at let one time Comparing and rect(mysize / 2, mysize / 2,, ); 10; Format: ( > 0); A Statement(s) loop always to be executes repeated at long let one time booleanexpression is true; Comparing Format: and Format: (booleanexpression) Statement(s) (booleanexpression); to be repeated long booleanexpression is true; Loop Format: Loop Loops6.pde Loops6.pde ; Looping Inside Loop draw() Function Effectively Loop any loop structure placed inside draw() function is a nested loop (an inner loop inside an outer loop) Loops6.pde Remember that Processing only s output display at conclusion of each draw() function Loops6.pde refore changes that occur during draw() not render until each of its iterations Looping is ne Inside executing draw() Function Loops7.pde Effectively any loop structure placed inside draw() function is a nested loop (an inner loop inside an outer loop) Loops7.pde Remember that Processing only s output display at conclusion of each Loops7.pde draw() function 3) refore changes that occur during draw() not render until each of its iterations Loops7.pde is ne executing 4) Loops7.pde MiniQuiz No. 2 Filename: Loops8.pde Loops7.pde Create an output winw 200 by 200 pixels Loops7.pde In draw() use a for loop to draw five circles 3) one on top of next with diameters 50, 40, 30, 20 and 10 pixels at x location (y is midpoint of output winw) Loops7.pde 4)