About C++

 

HISTORY OF C++ PROGRAMMING LANGUAGE

It is difficult to program in machine code and early computer pioneers soon developed the high-level languages which make the programming easier than before. One of these high-level languages is

C++.

The C++ programming language was developed by Bjarne Stroustrup(Bell laboratories) in early 1980s.

 

TIPS ON STANDARD LIBRARY

Using C++ Standard Library functions and classes instead of writing your own versions can improve

Program performance, because they are written carefully to perform efficiently. This technique also

shortens program development time.

THE PROCESSES OF CREATING A PROGRAM

The processes of creating a program include;

v  Write the program in a computer language that humans can read and understand (like C++).

v  Save the program in text files.

v  Run the source code files through a program called a compiler to generate object code for the target computer.

v  Run the object file through a program called a linker to produce an executable image

 

 

Three programs are used to translate your source code into an executable file that the computer can run. These programs are in their order of appearance:

§  Preprocessor

§  Compiler

§  Linker

PREPROCESSOR

The preprocessor is a program that scans the source code for preprocessor directives such as include directives. The preprocessor inserts into the source code all files included by the include directives.

 

COMPILER

The compiler is another program that translates the preprocessed source code (the source after the insertion made by the preprocessor) into corresponding machine language instructions, which are stored in a separate file called an object file, having an obj extension. There are different compilers for different programming languages, but the purpose of the compiler is essentially the same, the translation of a programming language into machine language, no matter which programming language is involved.

LINKER

While the object file has machine language instruction, the computer cannot run the object file as a program. The reason is that C++ also needs to use another code library, called the run time library, for common operations, such as the translation of keyboard input or the ability to interact with external hardware such as the monitor to display a message.

The linker is a third program that combines the object file with the necessary parts of the run-library. The result is the creation of an executable file with an .exe extension.

TYPICAL C++ DEVELOPMENT ENVIRONMENT

Phase: Creating a program

Phase 1 consists of editing a file with an editor program (normally known simply as an editor).  You type a C++ program (source code) using an editor, make any necessary corrections and save the program on a secondary storage device, such as your hard drive. C++ source code file names often end with the. Cpp, .Cxx, .CC or .C extensions.

Phase 2 And 3: Preprocessing and Compiling a C++ Program

In phase 2, the programmer gives the command to compile the program. In a C++ system, a preprocessor program executes automatically before the compiler’s translation phase begins. The C++ preprocessor obeys commands called preprocessor directives, which indicate that certain manipulations usually include other text files to be compiled and perform various text replacements.

Phase 4: Linking

Phase 4 is a called linking. C++ programs typically contain references to functions and data defined elsewhere, such as in the standard libraries or in the private libraries of groups of programmers working on a particular project. The object code produced by the C++ compiler typically contains “holes” due to these missing parts. A linker links the object code with the code of missing functions to produce an executable image (with no missing pieces). If the program compiles and links correctly, an executable image is produced.

Phase 5: Loading

Phase 5 is Loading.

Before a program can be executed, it must first be placed in memory. This is done by the loader, which takes the executable image from disk and transfer it to memory. Additional components from shared libraries that support the program are also loaded.

Phase 6: Execution

Finally, the computer, under the control of its CPU, executes one instruction at a time.

Programs do no always work on first try. Each of the proceeding phase can fail because of various errors. For example, an executing program might attempt to divide by zero (an illegal operation for whole-number arithmetic in C++). This would cause the C++ program to display an error message. If this occurs, you would have to return to phase-1 for editing, make the necessary corrections and proceed the remaining phases again to determine that the corrections fix the problem(s).