C++Builder Basics - Tutorial for Creating and Using a Static Library

Part I: Short Introduction

C++Builder provides several hundred classes, functions, and macros that you call from within your C and C++ programs to perform a wide variety of tasks. These classes, functions, and macros are collectively referred to as library routines. In addition to using the provided libraries, you may have the need to create you own libraries for use in your projects. This provides an easy interface for code reusability and allows you to consolidate related source code files into a single package. Also, consider that, because a library is a basically a collection of binary object files, the functionality encapsulated within the library is abstracted, such that users of the library are only able to view the interfaces to the functionality, but not the actual source code.

Conveniently, creating a static library is easy with C++Builder. This document provides the basic steps for building your own static libraries.

Part II. Building the static library from source and header files.

The following code samples represent the entirety of our static library example. Basically, our library will contain a class which has a integer data member which may be read or written using the public "getter" and "setter" functions. All declarations are found in the header file, and all of the implementation is kept in the source file.

A. Creation of your source and header files for the library.

Run Notepad, paste the following code into the editor, and then save the file as mylib.h (into an empty directory). This will be the header file:

//----------------------------------------------
#ifndef mylib_h
#define mylib_h

class A;

class A
{
   public:
      A();
      ~A() {};
      A(int newa);
      int getValue() const;
      void setValue(int newa);
   private:
      int a;
};

#endif
//----------------------------------------------

Now, do the same thing for the following code, but name the file, "mylib.cpp." This will be our source file.

//----------------------------------------------
#include "mylib.h"

class A;

A::A(int newa) : a(newa)
{
}

int A::getValue() const
{
  return a;
}

void A::setValue(int newa)
{
  a = newa;
}
//----------------------------------------------

B. Using the Library "wizard" to create the basic library.

Builder provides an easy way to generate a basic library. What you will be doing is creating a library using the Library Wizard, and then add the source file to it, and build. Here are the quick steps to follow:

1. File | Close All
2. File | New | Library
3. View | Project Manager
4. In the Project Manger, select Project1.lib, right-click and choose Add...
5. Navigate to the directory where you saved your files, and select "mylib.cpp"
6. File | Save All
7. Now you are ready to actually build the library, so: Project | Build
8. Your library is all ready to be used!

III. Using your static library

If you would like to use it in an application, please follow these steps:

1. File | Close All
2. File | New Application
3. File | Save Project As... | & choose a new directory (not where your library is)
4. Copy, "project1.lib" and "mylib.h" (from your library application folder) into the new directory you just saved your project in. Both of these files are necessary in order to use your library.
5. Project | Add to Project... | change the file type to .lib, and select your static library (now in the folder for this project).
6. In your Unit1.cpp file, you must include the header file, "mylib.h," like so:

         #include "mylib.h"
   

7. Now, don't expect fireworks, but to see the library actually work, place the following code in the OnCreate Event of the form:

           // Creates an object, A (from the library)
         A test(50);
         Form1->Caption = test.getValue();
   

8. If everything is as it should be, you should see a "50" appear as the form's caption.

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Archive of https://support.embarcadero.com/article/22694