What does a computer program look like?

In the old days scientists programmed computers by hand, manually turning on or off thousands of switches to perform a simple calculation.

It's gotten a little easier since then, but writing software can still be tedious. Software is made up of a "recipe" of detailed instructions the computer must follow to get it to perform the way you want. The recipe is called an "algorithm", and might look something like this:

for(int i = 1; i <= 10; i++)
{
Console.WriteLine("The number is: " + i.ToString());
}

The "code" shown above would write out the numbers 1 through 10 to a console window. But first it has to be "compiled" into machine code, a series of 1's and 0's, that the computer can understand. To do that, special software is used called a compiler. When the compiler is done doing its thing, it creates an executable file which you can run like any other program you have on your computer.

So what's with the 1's and 0's? The 1's and 0's are equivalent to the on and off switches computer scientists had to manually set decades ago. Every program that runs on a computer is ultimately reduced to thousands of on and off switches, but thankfully the compiler takes care of that for us.

If you want to have a go at creating your own computer programs, Microsoft has made available several "Express" editions of their Visual Studio development environment.

Click here to download Visual C# Express, which includes a compiler for the C# programming language.