Using C++ classes

If you did your first OOP related coding using Java or C# you may find bit uncomfortable when you trying to use classes in C++. Because syntax and structure has bit difference between them. So lets see how to write a class in C++. This is a basic tutorial as there is no much explained tutorial in the web.

Unlike Java or C#, you have to define your class in the header file of C++ project. Now go to the header file of your project and add following class definition.

class Car
{
       private:
                int noOfTyres;

       public:
              Car();
               void drive();
};

As you can understand I'm going to discuss a simple example here. In the private: section you have to define private variables / methods of the particular class. In the public: section you can define public methods/variables of the class. The methods should not have its body with the header file. It will contain in the cpp file. Also if you are going to include a constructor other than the default constructor, it should declared at the public section.

Now go to the cpp file and include the header file using the #include tag. Now you have to add method body. Just check the following code.

You can define the constructor of the Car class,

Car::Car()
{
      // constructing code goes here
}

Explanation:

The first "Car" term and the double colons (::) describes that the method is belongs to the "Car" class. Next Car() term describes the Car constructor.

Now lets define the drive() method,

void Car::drive()
{
       // code goes here
}

Explanation,

The first "void" term describes the return type of the method. It should be same as what you gave at the header file. From the next phrases of the statement, it describes that the drive() method is belongs to the Car class.(Car::drive()).

So I hope you understood.

Now think you wanted to add a variable of another class type into the Car class. As an example "Type" class belongs to the "Car" class. Then your header file should be shown as below.

class Tyre
{
        private:
               // private things goes here
        public:
              // public things goes here
};

class Car
{
         private:
               Tyre tyres;
         public:
               void drive();  
};

The most important thing is that you have to declare the "Tyre" class before declaring "Car" class. It is a good practice to follow that the two class should keep in two header files.

I hope you got some basic idea of using Classes in C++.

Image Source: http://obangarages.co.uk/wp-content/uploads/2011/09/Car-tyres-Oban-300x199.jpg

Integrate SQLite with Visual C++

MySQL, SQL Server and Oracle are the generally used database systems. But with the arrival of embedded and mobile devices, SQLite has become very useful. When you are doing a project using C or C++, SQLite will be the most suitable option according to the scale of your project. SQLite is a light weight database system. When I tried to integrate SQLite into my Visual C++ project, I realize that there is no proper documentation that make the developer's life easier. So I am going to explain my experience.

First download SQLite from the developer's web site. You have to download 

• sqlite-shell-win32-x86-3080100.zip  
• sqlite-dll-win32-x86-3080100.zip from the Precompiled Binaries for Windows section. 
• And sqlite-amalgamation-3080100.zip file from the same site.

Then extract all the zip files to one folder. Lets assume that folder is "C:\SQLite". 

Now add the path of that folder into the PATH variable of your computer.(Same procedure as you do it in Java jdk.)

Now open the Visual Studio Command Prompt which I mentioned in this post. Then type below command and press enter. This will create sqlite3 library file.

lib /DEF:"C:\SQLite\sqlite3.def" /OUT:"C:\SQLite\sqlite3.lib"

Now after that open your Visual C++ project using Visual Studio IDE. Then write click your project and goto Properties.

Then following window will appear.

Now go to the C/C++ section from the left tab. When selecting that, the right tab will change. Now add the path of your SQLite folder into the "Additional Include Directories".

Then go to the General section of the Linker from the left tab.(Linker -> General). Now again add the same path to the "Additional Library Directories".

Finally go to the Input sub section of the Linker (Linker -> Input) and add "sqlite3.lib" in to the Additional Dependencies. Then press OK.

Now you are done and you can do your coding.

First include the sqlite3.h header file using #include <sqlite3.h> code.

Then do your coding. Below code is extracted from this tutorial. It just opens and connects to a new database.

#include <stdio.h>

#include <sqlite3.h>

int main(int args, char* argv[]){

    sqlite *db;

    char *zErrMsg = 0;

    int rc;  

    rc = sqlite3_open("database_1.db", &db);

    if(rc){

      printf("Can't open databse: %s\n", sqlite3_errmsg(db));

      exit(0);

    }else{

      printf("Opened database successfully\n");

    }

    sqlite3_close(db);

}

Happy Coding! :)

Build your solution using Visual Studio Command Prompt

There are some solutions which generated automatically but with a large content. Also there are some buggy Visual Studio versions which are lagging and becomes non-responding while opening and building a comparatively larger solutions.

When I was building OpenCV and QT for my University Final year project, I faced same situation. (I will post a separate article about this OpenCV building process.) My Visual Studio version seems buggy and I didn't have enough time to re-install it. When I tried to open the OpenCV solution using Visual Studio IDE, it becomes non-responding. So I tried the Visual Studio Command Prompt.

Visual Studio Command Prompt

You can open Visual Studio Command Prompt using Visual Studio Tools in the Visual Studio in Start Menu. Then you have to execute just one command. It is simple.

MSBuild D:\Project\YourSolution.sln /p:Configuration=Release 

Replace the "D:\Project\YourSolution.sln" with the location of your solution. Execution will take some time according to the scale of your project. After building using above command, replace "Release" with "Debug" if you want to build your solution for the debug also.

Hope my post will helpful! :)