is the average of (1 + 2 + 3 + 4 + 5) / 5 Press Enter to terminate in C#.NET

Creation USS Code 128 in C#.NET is the average of (1 + 2 + 3 + 4 + 5) / 5 Press Enter to terminate

The VariableArrayAverage program begins by prompting the user for the number of values she intends to average The result is stored in the int variable numElements In the example, the number entered is 5 The program continues by allocating an array dArray with the specified number of elements In this case, the program allocates an array with five elements The program loops the number of times specified by numElements, reading a new value from the user each time After the user enters the values, the program applies the same algorithm used in the FixedArrayAverage program to calculate the average of the sequence The final section generates the output of the average along with the numbers entered in an attractive format (attractive to me beauty is in the eye of the beholder) Getting console output just right is a little tricky Follow each statement in the FixedArrayAverage carefully as the program outputs open parentheses, equal signs, plus signs, and each of the numbers in the sequence, and compare this with the output

The VariableArrayAverage program probably doesn t completely satisfy your thirst for flexibility You don t want to have to tell the program how many numbers you want to average What you d really like is to enter numbers to average as long as you want and then tell the program to average what you ve entered In addition to the array, C# provides other types of collections, some of which can grow and shrink as necessary; 15 describes these collections, which give you a powerful, flexible alternative to arrays Getting input directly from the user isn t the only way to fill up your array or other collection, either Bonus 2 on the CD describes how to read an arbitrary number of data items from a file

The for loop used to populate the array in the VariableArrayAverage program begins as follows:

// now declare an array of that size double[] dArray = new double[numElements]; // accumulate the values into an array for (int i = 0; i < numElements; i++) { // prompt the user for another double ConsoleWrite( enter double # + (i + 1) + : ); string sVal = ConsoleReadLine(); double dValue = ConvertToDouble(sVal); // add this to the array dArray[i] = dValue; }

The dArray is declared to be numElements in length Thus, the clever programmer (me) used a for loop to iterate through numElements of the array It would be a shame and a crime to have to schlep the variable numElements around with dArray everywhere it goes just so you know how long it is Fortunately, that isn t necessary An array has a property called Length that contains its length dArrayLength has the same value as numElements The following for loop would have been preferable:

// accumulate the values into an array for (int i = 0; i < dArrayLength; i++)

On the surface, the syntax of fixed- and variable-length arrays look quite a bit different, as follows:

double[] dFixedLengthArray = {5, 2, 7, 35, 65, 8, 1, 9, 1, 3}; double[] dVariableLengthArray = new double[10];

The difference is that C# is trying to save you some work C# allocates the memory for you in the case of the fixed-length array dFixedLengthArray You could have done it yourself using the following code:

double[] dFixedLengthArray = new double[10] {5, 2, 7, 35, 65, 8, 1, 9, 1, 3};

Here, you have specifically allocated the memory using new and then followed that declaration with the initial values for the members of the array

Programmers often must deal with sets of user-defined objects (classes) For example, a university needs some type of structure to describe the students who are attending the fine institution of higher learning Pfft! A bare-bones Student class appears as follows:

public class Student { public string sName; public double dGPA; }