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Control, Conditionals, Loops, Comments, Constants in Code

Learn about control structures like conditionals and loops, how to use comments for documentation, and declaring constants in code.

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Control, Conditionals, Loops, Comments, Constants in Code

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  1. Control Conditionals...Loops Comments...Constants

  2. The simple case if(<boolean_value>) single_statement; OR if(<boolean_value>) { statements; } Conditionals This can be dangerous!!!

  3. The Classic Killer Error if(<some_boolean>); { statement; statement; }

  4. Conditionals • Adding the else part: if(<boolean condition>) { statement; statement; } else { statement; statement; } Example: if( leapYear ) { febDays = 29; } else { febDays = 28; }

  5. Conditionals • Adding the else part: if(<boolean condition>) { statement; statement; } else { statement; statement; } Example: if( leapYear ) { febDays = 29; } else { febDays = 28; }

  6. Pseudocode total, i isoftype Num total <- 0 i <- 1 loop exitif(i > 10) total <- total + i i <- i + 1 endloop Java int total, i; total = 0; i = 0; while(i <= 10) { total = total + i; i = i + 1; } Loops -- Sentinel

  7. Pseudocode total, i isoftype Num total <- 0 i <- 1 loop total <- total + i i <- i + 1 exitif(i > 10) endloop Java int total, i; total = 0; i = 1; do { total = total + i; i = i + 1; } while(i < 10); Loops -- Test Last

  8. for Loops for(<init>; <while_boolean>; <inc>) statement; • <init> is done before entering loop • <while_boolean> is checked before entering and before each subsequent iteration and must be true • <inc> is performed at the end of each iteration. • Note: <init> and <inc> can be multiple statements but for now don’t do it!

  9. Classic while loop int total = 0; int i = 0; while(i < 10) { total = total + 1; i = i + 1; } for loop int total = 0; int i; for(i = 0; i < 10; i++) { total = total + 1; } Loops -- Convenience!

  10. Loops Summarized while(<boolean>) { statement(s); } do { statement(s); } while(<boolean>); for(<init>; <while_boolean>; <inc>) { statement(s); }

  11. Shorthand Operators • iCounter = iCounter + 1; OR iCounter++; • iCounter = iCounter - 1; OR iCounter--; • iCounter = iCounter + 2; OR iCounter += 2; • iCounter = iCounter * 5; OR iCounter *= 5;Last two examples: it’s “op” then “equals” (e.g., +=2), not “equals” then “op” (e.g., isn’t =+2) • These work with +, -, *, / plus others. • i++; // means increment i • i += 2; // means add 2 to the value of i • WARNING: THESE ARE NOT JUST CUTE TRICKS THEY ARE VERY POWERFUL AND CAN BE MISUSED. HANDLE WITH CARE!!!

  12. Documentation & Comments • Two ways to do it: // Double slashes comment out everything until the // end of the line /* Starts a comment which may extend multiple lines and eventually be terminated by */

  13. Constants • Pseudocode <CONST_ID> is <constant value> MIN_PASSING is 60 PI is 3.14159 • Java public final static <type> <IDer> = <value>; public final static int MIN_PASSING = 60; public final static float PI = (float) 3.14159; • Details on “why this syntax” to come soon...

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