4: Operators in C#.NET

Create Code 128 Code Set A in C#.NET 4: Operators

The compiler doesn t mind if you use them where they re not needed, and it may help to make the operation clearer to readers of your code. In some complex equations, you might need to nest parentheses to ensure the proper order of operations. For example, say you want to know how many seconds a hypothetical family wastes each morning. The adults spend 20 minutes over coffee each morning and 10 minutes reading the newspaper. The children waste 30 minutes dawdling and 10 minutes arguing. Here s the algorithm:

(((minDrinkingCoffee + minReadingNewspaper )* numAdults ) + ((minDawdling + minArguing) * numChildren)) * secondsPerMinute;

Although this works, it is hard to read and hard to get right. It s much easier to use interim variables:

wastedByEachAdult = minDrinkingCoffee + minReadingNewspaper; wastedByAllAdults = wastedByEachAdult * numAdults; wastedByEachKid = minDawdling + minArguing; wastedByAllKids = wastedByEachKid * numChildren; wastedByFamily = wastedByAllAdults + wastedByAllKids; totalSeconds = wastedByFamily * 60;

The latter example uses many more interim variables, but it is far easier to read, understand, and (most importantly) debug. As you step through this program in your debugger, you can see the interim values and make sure they are correct. See 9 for more information.

Summary

An operator is a symbol that causes C# to take an action. The assignment operator (=) assigns a value to an object or variable. C# includes four simple arithmetic operators, +, -, *, and /, and numerous variations such as +=, which increments a variable on the left side of the operator by the value on the right side. When you divide integers, C# discards any fractional remainder. The modulus operator (%) returns just the remainder from integer division. C# includes numerous special operators, such as the self-increment (++) and self-decrement (--) operators.

Summary

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To increment a value before assigning it, you use the prefix operator (++x); to increment the value after assigning it, use the postfix operator (x++). The same rule applies to the decrement operator. The relational operators compare two values and return a Boolean. These operators are often used in conditional statements. The conditional operator ( : ) is the only ternary operator found in C#. The test condition is found to the left of the question mark; it invokes the expression to the left of the colon if the tested condition evaluates true and the expression to the right of the colon if the tested condition evaluates false. The compiler evaluates operators according to a series of precedence rules, and parentheses have the highest precedence. It is good programming practice to use parentheses to make your order of precedence explicit if there may be any ambiguity. You saw a lot of math in this chapter, which is certainly useful, because your programs will often perform mathematical operations. We also mentioned several times that these operators will be useful in 5. 5 deals with branching, the technique by which you enable your program to take different actions depending on the values contained in the variables. 5 is going to tie together what you ve learned so far, and enable you to take the next step with your programming skills.

Question 4-1. What is the difference between the = and == operators Question 4-2. Suppose I have four different variables, a, b, c, and d. What s the shortest way to assign them all the value 36 Question 4-3. What s the difference between dividing two ints and dividing two doubles Question 4-4. What is the purpose of the % operator Question 4-5. What is the output of these operations 4*8 (4 + 8) / (4 2) 4+8/4 2