Programming basics : manage program flow final part

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Welcome reader,

This will be the final part in the programming basics mini series in how to manage the program flow of your software application. We’re going to see how to manage the flow of your program when we’re using a switch. It is a structure that is mostly use when we have predefined conditions.When this happen, knowing exactly those condition, we’ll have the correct operation to perform if it is met. For example, when someone is doing an exam, we could have three states

  1. He didn’t know what to do, so he had a 0
  2. The knowledge on the topic was not mastered he managed to get 11 out of 25
  3. The student mastered the topic and had 25 out of 25

If conditions like these we found in our application, it would be better to use a switch instead of the if-else if – else structure because we’ll have less to write. We’ll see below the structure of a switch statement :


/*

Everything in this code will not work

it is used to demonstrate how a switch statement is written

*/

switch (aVariable)
{
 case /*ValueOfAVariable*/:
        /*Operation*/;
 break; //tells the computer to stop the operation in this case
 default: //Represent what to do if no condition is met
        /*Operation*/;
}

In a swich statement, a case represents the value of the variable we’re evaluating in the switch. If a case is met, then all the operations for this case will be perform until the machine find the line with a break statement. Moreover, the cases can be link altogether. Like it was said before, until the computer find the statement “break;”, the switch will continue to operate. Below, we’ll see an example of such a switch:

switch(value)
{
   case 1:
   case 2:
   case 3:
   case 4:
     //do some stuff
     break;
  case 5:
  case 6:
    //do other stuff
    break;
  default:
      //do some default stuff
      break;
}

Also, we have the ternary operator, which embeds the way the if-else structure work. We’ll be able to find the structure of the ternary operator below for when you want to assign a value to a variable:

  • dataType variable = ( aCondition) ? (firstValue) : (secondValue) ;

The ternary operator evaluates the given condition. If it is true, firstValue will be assign to variable. If the condition was to be false in our program, then secondValue would be assigned to variable. We’ll try out a code sample to see how it could be useful:


int minValue=15;

int midValue=30;

int maxValue=45;

int aMaxValue=(midValue>maxValue) ? midValue : maxValue;

All of this covers how to manage the program flow in your software application. If for the moment this does not look useful, in the next posts,  it will get more clear as we get deeper into programming as our knowledge of the basics gets better.

Kevin

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Programming basics: My first console application

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Welcome reader,

We haven’t create an application since the start of the programming basics. It is sort of a ritual that the first program that a programmer writes will print of the screen the following : “Hello World!”. So, we are actually going to write this as our first console application.

Open your IDE and select Console application. Copy paste the follow code below and hit the run button in your IDE :

public static void Main()
   {
      System.Console.WriteLine("Hello, World!");
   }

There, you have the most basic application you can create. You are actually using a method called “WriteLine” and putting information inside the parenthesis. This information that was passed as a parameter (they will be discussed at length during the method post) was then written on your screen.

There you go ! It wasn’t so bad, you can now call yourself a “developer” or a “programmer”. As we’ll progress, you’ll see that programming isn’t so hard as long as you put your time in it and really want to learn. Being passionate about what you’re trying to achieve will help you to master a lot of subjects. Don’t beat yourself down if there was ever a subject that eluded you even if it was the 100th that you tried to do it. Take some time off and come back, make sure you understand the core fundamentals before moving foward !

Kevin

Programming basics: naming convention, indent and white spaces

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Welcome reader,

We’ll follow where we left off when we’ve talked about variables. When you are behind you screen, there is a lot more going on then just writing lines in the IDE to make you computer do something.  There are a set of rules that you should always stick to make your code clearer. Before, we talked about commenting your code.  Comments are meant to explain the purposes of your program. As an example,  when you’re creating variables, placing comments can help explain what you’re trying to do with those variables. When you’re programming, your instructions will be read by the IDE. Comments will be ignore by the IDE.

There are different ways to comment code. You can place comment on one line. You can also you what I call paragraph commenting. These will come handy when we’ll describe the behavior of methods. You’ll find some commenting examples.


//This is a single line comment

/*

This a paragraph comment. While I'm inside the /**/

all that will be written will be ignored by the IDE

*/

int myIntVariable; //Explain the usefulness of your variable with this comment 

More than just comments, there are other ways to make sure that other programmers who might read your code will appreciate reading it. As you could have seen, when I’m writting my variables, I follow a set of rules which I strongly suggest that you should also follow. This is called the “camelCase” convention. When you’re creating something like a variable or a method (more on methods later), these are the rules that you’ll have to follow.

  • The name of your variable cannot start with a number such as “123MyVariable”
  • The name of the variable should always start with a lower case letter such as “myVariable”
  • When you’re trying to write a composed name, you can either do this : “thisIsTheNameOfTheVariable” or use the underscore to separate either word of the variable’s name like this :  “this_Is_The_Name_Of_The_Variable”
  • Never forget to give a meaningful name to your variable

Finally, even following those set of rules is not quite enough. A good programmer should always indent his code a have a moderate use of white spaces. Well, I’ve just blurred some words that won’t really mean something to you so I’ll explain what I’m trying to tell you. Indenting code is a convention where you place tabs in the blocks of code. As for white spaces, there just meant to make code easier to read. It could all be close together, but that wouldn’t do any good if one must spend some time, trying to decrypt what you’ve wrote.

You’ll find below an example :

/*
The following block of code won't work
It will serve as an example to make sure
that you understand indentation
*/
//indentation
int variable_1=10;
{
   int variable_2=13; //See? There was a tab after the curly brace
}

//white spaces(none)
int variable_3=15;
double variable_4=20.0;
decimal variable_5=0.05m;
short variable_6=56;

//white spaces
/*
Putting white before and after operators(more on them later)
is helpful. Your code does not have to be too cramped
More than just that, separate your variables makes it also easier to read

What I suggest is if you have a set of variables that have a relation
altogether, let them be in a group but after create an empty line and then
resume your coding activity
*/
int variable_7 = 123;

double variable_8 = 234.98;

decimal variable_9 = 0.45m;

Programming basics : variables

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Welcome reader,

This is the first part of a mini-serie to introduce the basics of programming with C#. Don’t forget to look at my GitHub account. I haven’t decide yet, but surely I will create a project which will resume every topic that I’ve talked about during the Programming basics serie.

So, we’re finally there, will start talking about the programming at last! In this serie, I assume that you’ll have already downloaded your IDE( if you don’t know what’s an IDE, please go read my blog post about IDEs) on your machine. Like I have mentionned before, I’ll be using the Visual Studio Community Edition IDE in this blog.

The introduction to programming start with a fundemental topic : variables. When you are programming, you are telling your machine exactly what you want it to achieve. In order to do so, you have to manipulate data directly on your machine, and when you’ll be running your software application(more of running later), the code that you’ve given will look like this:

0101010 0101 010101 01010

For the untrained eyes, it’s only 0s and 1s. But that is called binary code. This is what your machine use to achieve an operation that you have order it to do.  Even when you are on your user interface of you operating system, you are telling your computer what to achieve for you such as

Opening a folder

Save a file

With the IDEs,  our life is easier, we don’t need to actually manipulate data on the computer with binary code, we use variables. What this means is this: variables points to different parts of the computer memory. In short, variables have a name and a value.They hold different kind of data which can be manipulate and consume by a programmer in order to achieve his goal. Below, you’ll be able to see all the variables that are accessible in most programming languages:

  • byte – 8 bits
  • short – 16 bits
  • int – 32 bits
  • long -64 bits
  • float – single precision 32 bit floating numbers
  • double – double precision 64 bits floating numbers
  • decimal – 16 bits
  • bool – boolean value (true/false)
  • char – holds a character
  • String (it will be discussed in a later post)

From byte to long, these represent integer values such as 0, 100, 200. We have access to different kind of integer values, and when you are programming, you have to choose carefully the exact type you need because each type has its own weight in bit. The more you use, the bigger the software application will be. To understand the difference between the type of integer you can choose, you will find below the range of values each one has:

  • byte [0,255]
  • short [-32768,32767]
  • int [-2147483648,2147483647]
  • long [-9223372036854775808,9223372036854775807]

For example, if you create a software application which will only hold employees ages, using long variables because of their weight. Rapidly, in an application with around a million employees, the software would be heavy to process because you’re using the wrong type of data. In this case, knowing that the human’s span life is around 80 years, using the byte type would be much better. While using variables, you should always use your judgement in order to be memory efficient. Lower, you’ll be able to find an example of a byte variable containing the age of an employee:


byte employeeAge=30;

As you can see, when using a variable, the variable’s name is on the left and the value,which will be assigned, is on the right.  To continue, the float,double and decimal types should be use only when you to consume data which contained the full value of number like 1.25.


int firstValue=1.25; //firstValue will only be 1 because it is an integer
float secondValue=1.25; //secondValue will be 1.25

Console.WriteLine(firstValue);//Will display the value of 1
Console.WriteLine(secondValue); //Will display the value of 1.25

Upward, you can see some code sample showing the use of two variables and C# function(more on functions later) in order to display data to the screen. There’s quite a lot going on in this sample, the part with the double slash is called comments. Comment will be discussed in the next part of this serie. Moreover, as you can see, the names of the variable don’t really represent anything. When using variables, the names you use should always be meaningful. By always doing so, you’ll be able to understand the code you’ve written a while back faster without, or almost, need of comments.

To finish, the char type can only hold a character as a value. A character can be anything such as a alpha or numerical character. The char data is assigned with single quotes. You can see an example below.


byte charVariable='1';

To wrap up, variables have a meaningful name and a value. When using variables in your software application, you should make sure to always use the right type in order to be memory efficient.

Kevin