The First Exercise

The first item in Prashant’s list of 15 Exercises for Learning a new Programming Language is:

Display series of numbers (1,2,3,4, 5....etc) in an infinite loop. The program should quit if someone hits a specific key (Say ESCAPE key).

So this post we start to look at loops and integer types.

Here’s my solution to the exercise:

using System;

class MainClass
{
    static void Main()
    {
        ulong lCount = 0;
        while (true)
        {
            Console.WriteLine((++lCount).ToString());
            if (Console.KeyAvailable && Console.ReadKey(true).KeyChar == '\x1B') break;
        }
    }
}

C# has 8 integer types:

Type	Bits	Min Value	Max Value
byte	8	0	256
sbyte	8	-128	127
ushort	16	0	65,366
short	16	-32,768	32,767
uint	32	0	4,294,867,295
int	32	-2,147,483,648	2,147,483,647
ulong	64	0	18,446,744,073,709,551,615
long	64	-9,223,372,036,854,775,808	9,223,372,036,854,775,807

I’ve chosen to use a ulong to store the number we’re going to display, because it will give us the highest count.  Of course, you’d have to wait a while before the count reached the limit of a short, but what the heck. 

Looping constructs in C# are, by-and-large, the same as in C and C++.  Here I’ve used while (true) {} to create an infinite loop.

In the next line we see something new.  In C# all types (with one exception) are inherited from the object type.  Thus, even basic integer types have a few basic methods, one of which is ToString. Using this we can increment the counter, convert the result to a string, and then write that string to the console.

The next line uses the Console class to check for the Escape key being pressed.  Console.KeyAvailable returns true if there is a key available in the keyboard buffer, that is, a key has been pressed.  The && operator (“and-also”) only evaluates the right-hand expression if the left-hand one is true.  So, if a key has been pressed we then get the character associated with the key and compare it to the escape character (‘\x1b’).

That’ll do it for this post, I think.  Next time I’ll have a look in more detail into C#’s type system and play around a bit with the integer types, and in the post after that we’ll tackle Exercise 2.