C# 4 and .NET 4

154 ❘ ChaPTer 7 OperAtOrs And cAsts
The prefix and postfix operators --x and x-- behave in the same way, but decrement rather than
increment the operand.
The other shortcut operators, such as += and -=, require two operands, and are used to modify the value
of the first operand by performing an arithmetic, logical, or bitwise operation on it. For example, the next
two lines are equivalent:
x += 5;
x = x + 5;
The following sections look at some of the primary and cast operators that you will frequently use within
your C# code.
The Conditional operator
The conditional operator (:), also known as the ternary operator, is a shorthand form of the if...else
construction. It gets its name from the fact that it involves three operands. It allows you to evaluate a
condition, returning one value if that condition is true, or another value if it is false. The syntax is
condition true_value: false_value
Here, condition is the Boolean expression to be evaluated, true_value is the value that will be returned if
condition is true, and false_value is the value that will be returned otherwise.
When used sparingly, the conditional operator can add a dash of terseness to your programs. It is especially
handy for providing one of a couple of arguments to a function that is being invoked. You can use it to
quickly convert a Boolean value to a string value of true or false. It is also handy for displaying the
correct singular or plural form of a word, for example:
int x = 1;
string s = x + " ";
s += (x == 1 "man": "men");
Console.WriteLine(s);
This code displays 1 man if x is equal to one but will display the correct plural form for any other number.
Note, however, that if your output needs to be localized to different languages, you will have to write more
sophisticated routines to take into account the different grammatical rules of different languages.
The checked and unchecked operators
Consider the following code:
byte b = 255;
b++;
Console.WriteLine(b.ToString());
The byte data type can hold values only in the range 0 to 255, so incrementing the value of b causes
an overflow. How the CLR handles this depends on a number of issues, including compiler options, so
whenever there’s a risk of an unintentional overflow, you need some way of making sure that you get the
result you want.
To do this, C# provides the checked and unchecked operators. If you mark a block of code as checked, the
CLR will enforce overflow checking, and throw an OverflowException if an overflow occurs. Let’s change
the code to include the checked operator:
byte b = 255;
checked
{
b++;
}
Console.WriteLine(b.ToString());
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