1. Arithmetic Operators
   • Basic binary operators
     • a + b (addition)
     • a – b (subtraction)
     • a * b (multiplication)
     • a / b (division)
     • a % b (modulo, i.e. remainder)
   • Basic unary operators
     • +a (unary plus)
     • -a (unary negation)
     • a++ (postfix increment by 1)
     • ++a (prefix increment by 1)
     • a– (postfix decrement by 1)
     • –a (prefix increment by 1)
2. Conditional Operator
   • The conditional operator is like an in-situ if test – (condition) ? trueResult : falseResult
   • Example:
     bool isMale;
int age;
...
int togo = (isMale) ? (65 - age) : (60 - age);
cout << "You have " << togo << " years to retirement";

3. Assignment Operators
   • Basic assignment operator
     • a = b (assign b to a)
     • Performs widening conversion implicitly, if needed (see later)
   • Example:
     int a = 100;
int b = 200;
b = 42;
a = b;
// OR
int a, b, c;
...
a = b = c = 0;

   • Compound assignment operators:
     • a += b (calculate a + b, then assign to a)
     • a -= b (calculate a – b, then assign to a)
     • a *= b (calculate a * b, then assign to a)
     • a /= b (calculate a / b, then assign to a)
     • etc…
   • Example:
     // Use *= compound operator:
x *= a + b;
// Equivalent to the following (note the precedence):
x = x * (a + b);

4. Casting
   • Implicit conversions:
     • C++ implicitly converts less-precise expns to more-precise expns
     • char -> short -> int -> long -> float -> double
   • Explicit conversions (aka casting):
     • You can explicitly cast an expression into a compatible other type
     • (type)expression –or– type(expression)
     • Might result in a loss of precision
   • Explain the following example: What would happen? can you do this without explicit casting?
     int judge1Score;
int judge2Score;
int judge3Score;
...
double averageScore = (double) (judge1Score + judge2Score + judge3Score) / 3;

5. Relational Operators
   • There are 6 relational operators (all return bool):
     • == (equality)
     • != (inequality)
     • >(greater-than)
     • >= (greater-than-or-equal)
     • < (less-than)
     • <= (less-than-or-equal)
6. Logical Operators
   • There are 3 relational operators (all return bool):
     • && (logical AND)
     • || (logical OR)
     • ! (logical NOT)
   • Note:
     • && and || perform short-circuit evaluation
7. Bitwise Operators
   • Bitwise AND and OR binary operators
     • & (bitwise AND)
     • ^ (bitwise exclusive OR)
     • | (bitwise inclusive OR)
   • Bitwise NOT unary operator
     • ~ (bitwise NOT)
   • Bitwise shift operators
     • << (shift bits left)
     • >> (shift bits right)
8. Order of Precedence
   • Operators have the following precedence (use parens to override this precedence):

   

`

1. Using operators
   • Start Visual Studio, and create a new C++ project named Dates in the student folder. Write code to manipulate day, month, and year values using operators. Suggestions and requirements:
     • To start off with, declare 3 integers with hard-coded values for the day, month, and year.
       // Declare 3 variables, for a hard-coded date.
int day = 3, month = 12, year = 2011;

     • View code file.
     • Use a conditional operator (?:) to determine if it’s a leap year. A leap year is: (evenly divisible by 4 AND NOT evenly divisible by 100); Use the remainder operator (%) to help you out here
       // Is the date a leap year?
bool isLeapYear = ((year % 4 == 0) && !(year % 100 == 0)) || (year % 400 == 0);
cout << "Is " << year << " a leap year? " << isLeapYear << endl;

     • View code file.
     • Test whether your “is-leap-year” algorithm works for various years.

1. Using if Tests
   • Basic if tests
     if (test) {
 body
}


   

   • if-else tests
     if (test) {
 body1
} else {
 body2
}


   

   • if-else-if tests
     if (test1) {
 body1
}
else if (test2) {
 body2
}
else if (test3) {
 body3
}
...
else {
 lastBody
}

   • Notes:
     • Test conditions don’t have to be bool
     • {} are optional if you want a 1-line statement
2. Nesting if Tests
   • You can nest if tests inside each other
     • Use {} to ensure correct logic, as needed
     • Use indentation for readability
       int age = ... ;
string gender = ... ;
if (age < 18) {  if (gender == "Male") {   cout << "boy" << endl;  } else {   cout << "girl" << endl;  } } else {   if (age >= 100) {
   cout << "centurion ";
  }
 if (gender == "Male") {
  cout << "man" << endl;
 } else {
  cout << "woman" << endl;
 }
}


     

3. Using switch Tests
   • The switch statement is useful if you want to test a single expression against a finite set of expected values
   • General syntax:
     switch (expression) {
case constant1:
 branch1Statements;
 break;
case constant2:
 branch2Statements;
 break;
...
default:
 defaultBranchStatements;
 break;
}

   • Expression must be:
     • Integral type (or enum)
     • Note, strings are NOT allowed!
   • Cases:
     • Must be (different) constants
   • If you omit break:
     • Fall-through occurs
   • The default branch:
     • Is optional
     • Doesn’t have to be at the end!

1. Using conditional logic
   • Validate the day, month, and year. Output a single message saying if the date is valid. If the date is valid, output it in the format dd/mm/yyyy. Suggestions and requirements:
     • Write an if-statement to validate the month (it must be 1-12).
        // Is the date valid?
 bool isValid;
 if (month < 1 || month > 12)
 {
  isValid = false;
 }

     • Write an if-statement to validate the year (let’s say the year must be 1900…2099).
        else if (year < 0 || year > 2099)
 {
  isValid = false;
 }

     • Write an if-statement to ensure the day is 1 or higher.
        else if (day < 1)  {   isValid = false;  }
     • Write a switch-statement to ensure the day isn't too big. The max value is 28, 29, 30, or 31, depending on the month (and if the month is February, whether it's a leap year).
        else
 {
  int maxDay;
  switch (month)
  {
   case 2: 
    maxDay = (isLeapYear) ? 29 : 28;
    break;
   case 4:
   case 6:
   case 9:
   case 11:
    maxDay = 30;
    break;
   default:
    maxDay = 31;
    break;
  }
  isValid = (day <= maxDay);  }  cout << day << "/" << month << "/" << year << " is valid? " << isValid << endl;
     • View code file.

1. Using while Loops
   • The while loop is the most straightforward loop construct
     • Test is evaluated
     • If true, loop body is executed
     • Test is re-evaluated, etc...
       while (test) {
 loopBody
}


   

   • Note:
     • Loop body will not be executed if test is false initially
   • How would you write a while loop...
     • To display 1 - 5?
     • To display the first 5 odd numbers?
     • To read 5 strings from the console, and output in uppercase?
2. Using do-while Loops
   • The do-while loop has its test at the end of the loop
     • Loop body is always evaluated at least once
     • Handy for input validation
     • Note the trailing semicolon!
       do {
 loopBody
} while (test);


   

   • How would you write a do-while loop
     • To keep reading strings from the console, until the user enters "London", "Oslo", or "Amsterdam" (in any case)?
3. Using for Loops
   • The for loop is the most explicit loop construct
     • Initialization part can declare/initialize variable(s)
     • Test part can incorporate any number of tests
     • Update part can do anything, e.g. update loop variable(s)
     • You can omit any (or all!) parts of the for-loop syntax
       for (init; test; update) {
 loopBody
}

4. Unconditional Jumps
   • You can perform an unconditional jump within a loop
     • break
       • Terminates innermost loop
     • continue
       • Terminates current iteration of innermost loop, and starts next iteration
       • If used in a for loop, transfers control to the update part
     • return
       • Terminates entire method

     for (initialization; test; update) {
 ...
 if (someCondition)
  break;
 ...
 if (someOtherCondition)
  continue;
 ...


   • Note: C++ also has a goto statement...

1. Using loops
   • Refactor your application so that it gets a series of dates from the user, rather than having a single hard-coded date. Suggestions and requirements:
     • Write a do-while loop that allows the user to enter a series of different dates. Each time round the loop, ask the user whether he/she wants to continue (use string here); if the user says "Yes" or "yes", keep on iterating
        int day, month, year;
 string response;
 do
 {
  // Get a date from the user and Error check
  ...
  // Ask the user whether he/she wants to enter another date.
  cout << endl << "Enter another date? ";
  cin >> response;
 }
 while (response == "yes");
 cout << "The End." << endl;

     • View code file.
     • Inside the loop, ask the user to enter a new day, month, and year
         cout << "Day: ";
  cin >> day;
  cout << "Month: ";
  cin >> month;
  cout << "Year: ";
  cin >> year;

     • View code file.
     • For each date, validate it as you did in Exercise 2 above