Chapter 3 - Controlling the Flow, Converting Types, and Handling Exceptions

  1. Where would you look for help about a C# keyword?
  2. Where would you look for solutions to common programming problems?
  3. What happens when you divide an int variable by 0?
    • A DivideByZeroException is thrown when dividing an integer or decimal.
  4. What happens when you divide a double variable by 0?
    • The double contains a special value of Infinity. Instances of floating-point numbers can have special values--NaN (not a number), PositiveInfinity, and NegativeInfinity.
  5. What happens when you overflow an int variable, that is, set it to a value beyond its range?
    • It will loop unless you wrap the statement in a checked block in which case an OverflowException will be thrown.
  6. What is the difference between x = y++; and x = ++y;?
    • In x = y++;, y will be assigned to x and then y will be incremented, and in x = ++y;, y will be incremented and then the result will be assigned to x.
  7. What is the difference between break, continue, and return when used inside a loop statement?
    • The break statement will end the whole loop and continue executing after the loop, the continue statement will end the current iteration of the loop and continue executing at the start of the loop block for the next iteration, and the return statement will end the current method call and continue executing after the method call.
  8. What are the three parts of a for statement and which of them are required?
    • The three parts of a for statement are the initializer, condition, and incrementer. The condition is required to be an expression that returns true or false, but the other two are optional.
  9. What is the difference between the = and == operators?
    • The = operator is the assignment operator for assigning values to variables, and the == operator is the equality check operator that returns true or false.
  10. Does the following statement compile? for ( ; true; ) ;
    • Yes. The for statement only requires a Boolean expression. The initializer and incrementer statements are optional. This for statement will execute the empty ; statement forever. It is an example of an infinite loop.

Exercise 3.2

  1. What will happen if this code executes?
            int max = 500; 
        for (byte i = 0; i < max; i++) 
        { 
            WriteLine(i); 
        }
    • The code will loop nonstop because the value of i can only be between 0 and 255, so once it gets incremented beyond 255, it goes back to 0 and therefore will always be less than max (500).
    • To prevent it from looping nonstop, you can add a checked statement around the code. This would cause an exception to be thrown after 255, like this:
          254
      255
      System.OverflowException says Arithmetic operation
      resulted in an overflow.
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