1. Chapter 4 October 22, 2013

2. The If Statement Programs make decisions If(condition){ Statement(s); } Condition  boolean expression Evaluates to either true or false  formed using relational operators

3. The If Statement OperatorMeaning = = equal to < less than <= less than or equal to > greater than >= greater than or equal to != not equal to

4. Statement  single or complex  Directions on what to do Pitfalls  do not use = = or ! = with decimals  roundoff errors occur because doubles cannot be exactly represented in binary The If Statement

5. Only compare values of the same type Do not confuse assignment (=) with equal to (==).  Will compile but output will vary Misplaced semicolons  if(score ==21); The If Statement

6. If-Else Statement Contains an else clause  Excuted when if is false If(condition){ statement(s); } else{ statement(s); }

7. More than one statement enclosed in { } Ex: if(temp > 5){ cout<<“Wear a coat!”<<endl; cout<<“It is cold outside”<<endl; } Compound Statements Nested if Statements Controls flow in 3 or more situations if statement within an if statement

8. If statement within an if statement If(condition){ if(condition){ statement(s); } Ex: if(temp < 5){ if(temp< 2){ cout<<“Wear a coat”<<endl; } Nested if Statements

9. Dangling else  A logic error associated with nested if statements  reason we use brackets clarify and group Nested if Statements Ex: if(temp < 5) if(temp< 2) cout<<“Wear a coat”<<endl; else cout<<“It’s hot”<<endl;

10. Else-if Ladder Decides between three or more actions order of if and else is very important Last statement is executed iff the statements before ALL fail. Ex: if(temp < 0) else if (temp< 2) else if (temp < 4) else

11. if(condition){ statement(s); } else if(condition){ statement(s); } else{ } Else-if Ladder

12. Logical Operators Used to form Boolean expressions && represents and | | represents or Evaluated based on the following rules

13. True/FalseOperator T/FExpressions T && TT T && FF F && TF F && FF Logical Operators &&- AND

14. OR –If example If((condition) | | (condition)){ statement(s); } If((temp 20 )){ cout<<“It’s really cold!!”<<endl; }

15. AND –If example If((condition) && (condition)){ statement(s); } If((temp 20 )){ cout<<“It’s too cold to be outside”; cout<< endl; }

16. Looping Control program through iteration  Repeat one or more statements  Referred to as looping

17. Do-while do { statement(s); }while(condition); Condition  Boolean expression  Determines if loop continues

18. Do-while executed at least once  condition executed after first loop if condition is true then statements are executed again and condition is reevaluated.

19. while Statements evaluates before each loop  Can be executed 0 or more times while(condition){ statement(s); } if the condition is true then the statements are executed and the condition is reevaluated until condition is false.

20. Infinite loops Continue FOREVER Causes  misplaced semicolons  missing curly brackets  logic errors

21. Algorithms series of steps that tell how to solve a problem usually written out first helps with structure of code helps eliminate logic errors  caused by statements that are syntactically correct but produce undesired results

22. Counting and Summing Counting  counts the number of values entered by the user  really counts number of loops  numOfValues = numOfValues + 1; takes values currently in variable, adds one to it and re-stores that sum in the original variable.

23. Counting and Summing Counting  counters variables that count need to be initialized gives it a starting value; usually 0 int i = 0;

24. Counting and Summing Summing  sums the values entered by a user  sumOfValues = sumOfValues + value; takes value currently stored and adds the new value and re-stores it back in sumOfValues  needs to be initialized usually zero.

25. Counting and Summing Sentinel  constant  value the loop should end on  Easily changed

26. Increment and Decrement ++  after a variable indicates addition of 1  numOfValues++; adds one and re-stores new value in numOfValues  increment operator  Where C++ came from

27. Increment and Decrement +=  adds a value to a sum  sumOfValues +=Value; adds value to sumOfValues stores new value in sumOfValues.

28. Increment and Decrement --  subtraction of 1 from variable  total --; subtracts 1 from total stores back in total - =  subtracts a value from a total  total -=value; subtracts value from total Stores new value in total

29. The for Statment executes a loop for a fixed number of times for(initialization; condition; increment){ statement(s); } initialization  performed once  type counter = startingPoint; int x = 0;

30. The for Statement Condition  Boolean Expression  Evaluated before each loop increment  performed after each loop  Advances the counter

31. The for Statement Initialization can be performed outside the loop  ex: int x = 0; for(; condition; increment){ statement(s); }

32. #include using namespace std; int main() { for ( int x = 0; x < 10;x++) { cout<< x <<endl; } }

33. The bool Library Boolean variables only hold true or false  library used to implement bool type  #include using namespace std; bool Tuesday = false;  no quotations marks