Building Blocks...

When thinking about how to build a program, you need some vocabulary and some pieces to build programs out of. There are a relatively small number of basic building blocks to build programs out of:

  1. Data
  2. Control Structures
  3. Loops
  4. Data structures
Each one of these deserves and needs extensive explanation. But first, here is a quick overview of these.

To start - lets talk about about data.

In order to make sure that we don't make this specific to any particular language I will just talk about fairly basic data types:
  • Integers (whole numbers)
  • Reals (decimal numbers)
  • Booleans (true or false)
  • Strings (text)
With these four types (possibly in combination) you have enough to store just about anything that you need to.

Control Structures provide you a way to decide which section of code is run based on some condition. Examples of control structures are:
  • If Then
  • If Then Else
  • Case (or Switch)
The If-Then lets you run a block of code only if some condition is true. If-Then-Else allows you to run either one block of code or another depending on the value of some condition. The Case allows you to choose between several specific values to decide which block of code to run.

Loops let you run the same block of code zero or more times. There are two basic versions:
  • For loops
  • While loops
A For loop would be used when you know exactly how many times you want to run block of code. A While loop lets you run the block of code until some condition occurs.

Finally, Data Structures allow you to combine multiple smaller individual pieces of data together. The simplest data structure is an Array. An array is basically a numbered list which allows you to access any entry by using its position in the list as an index. As a starting point - just the array is enough to begin. Data structures are actually a very extensive subject that has entire books written about them.

And that is the basic vocabulary that I will be using.

Next time, I'll be talking about constants and variables - the two ways to have data available to your program.

Comments

Post a Comment

Popular posts from this blog

Is trying to program making you loopy...?

So we've discussed two of the main building blocks of programming: Data and Control Structures. With those, you can do things once for every time your program runs. Well what if you want to do more than once and done? Loops. As I've mentioned before, there are two basic kinds of loops. One kind runs a particular number of times that the program 'knows' in advance. The other type runs until some condition becomes true. That first kind is a For loop. Here is an example of how you would use one...Suppose you wanted to print out the numbers from one to one hundred. The pseudo-code: For the numbers 1 to 100 Print the number Sort of a trivial use though. How about if we want to also print out whether the number is even or odd: For the numbers 1 to 100 If the number is even Print the number and the word even Else Print the number and the word odd Did you just feel a twinge of excitement? The pieces are starting to come together... Let'...
Read more

Laid out (arrayed) out before you...

We're at the last building block - data structures! But, there is no way to cover every kind of data structure because it is possible for anyone (even you) to make a new one at any time. So instead, we will start with the Array. Just about every programming language includes a built in type that corresponds to an array and the defining characteristic of an array is that each element stored in it can be referenced by an index number that counts up from index [0] and goes up through index [n-1] where 'n' is the number of elements in the array. Usually, there is an easy way to know how many elements there are in an array with some sensible name like 'size', 'length', or 'len'. That is a bunch of words, so let's see a simple example of an array called 'example' with ten elements in it. Here is the list of all of the elements along with their indexes (indices?): example[0] example[1] example[2] example[3] example[4] example[5] e...
Read more

Constants and Variables....

So, you want to make a computer do something useful. Well, then data is going to be involved one way or another. Even the simplest programs (like 'Hello World') deal with data! Some of it might be invisible to you - but it is there. Let's take a look at Hello World. First of all, if you don't already know - the objective of this 'first' program whenever you are beginning to program in a new language is to print out 'Hello World!' (or some variation of that). We may as well take a look at the objective to figure out what the algorithm and pseudo-code would be for this. First the algorithm: Open a connection to some output device (usually the screen) Print the string 'Hello World!' Close the connection Most programming languages automatically open a connection to the screen for you so this step is almost always ignored. But if you think about the fact that it is happening (even if behind the scenes) then it will make your life eas...
Read more