1. Flow Control Statements
Change the natural flow of a program from statement to statement.
Two types:
Decision-making: make a decision to either execute or not execute a set of code.
Repetition: make a decision to execute a set of code again.

2. Boolean Expressions
A program makes a decision using a Boolean expression that evaluates to either true or false.
Boolean expressions are formed with relational and logical operators.

3. Relational Operators == Equal to != Not equal to > Greater than
< Less than
>= Greater than or equal to
<= Less than or equal to
Make sure they understand relational expressions involving chars.

4. Logical Operators
Allow the combination of simple boolean expressions to make complex expressions.
&& Boolean And
|| Boolean Or
! Boolean Not
And and Or truth tables
Examples on board

5. if ( boolean expression ) statement;
double hours, otHours = 0;
cout << "Enter number of hours worked: ";
cin >> hours;
if( hours > 40 )
otHours = hours – 40;
cout << "You worked " << otHours << " overtime hours.";

6. if ( boolean expression ) { statement1; statement2; statement3; etc… }
double hours, otHours = 0;
cout << "Enter number of hours worked: ";
cin >> hours;
if( hours > 40 ) {
otHours = hours – 40;
cout << "You worked " << otHours <<
" overtime hours." << endl; }
HANDOUT – ifDemo.cpp

7. if( boolean expression ) statement(s) else
int years;
cout << "Enter your age in whole years: ";
cin >> years;
if( years >= 65 ) {
cout << "You’re qualified for Social Security.";
cout << "My, you’re old." << endl; }
else
cout << "You’re not that old." << endl;
cout << "Have a nice day." << endl;
HANDOUT – paycalc.cpp

8. if(action == 'd')
if(amount > 0)
balance += amount;
else
cout << "You have to deposit something." << endl;
if(balance >= amount)
balance -= amount;
cout << "Account is OVERDRAWN." << endl;
if( x == 7 )
if( y == 10 )
cout << "Both conditions are true." << endl;
if( x == 7 && y == 10 )

9. cout << "Both conditions are true."; else
if( x == 7 && y == 10 )
cout << "Both conditions are true.";
else
cout << "One or both of the conditions are false.";
if( x == 7 )
if( y == 10 )
cout << "Second condition is false.";
cout << "First condition is false.");
HANDOUT - lettergrade.cpp

10. bool eligible, survivor; int age; . . . eligible = false;
if(survivor == false)
if(age > 65)
eligible = true;
else
bool eligible,
survivor;
int age;
. . .
eligible = false;
if(survivor == false)
if(age > 65)
eligible = true;
else
The left is what I want
The right is what the compiler sees.
How to fix it?

11. bool eligible, survivor; int age; . . . eligible = false;
if(survivor == false) {
if(age > 65)
eligible = true; }
else
An if in one statement block can't be matched to an else in another statement block.
So enclose the offending if in it's own block

12. switch( integral expression ) { case <literal1>: statement1;
break;
case <literal2>:
statement3;
statement4;
default:
statement5;
statement6; }
switch is the only flow control statement that doesn't use Boolean expression to make decision.
Can't switch on a floating point value, or a string.
If there is no default case, and the value of the switch expression doesn't match one of the cases, nothing executes.
HANDOUT - calculator.cpp
calculator_fixed.cpp
payroll.cpp