c-and-cpp.md

C and CPP

In general, computer languages deal with two concepts: data and algorithms. The data constitutes the information a program uses and processes. The algorithms are the methods the program uses.

         +-------+         +--------------------+
         | Data  |         |    Algorithms      | 
         +-------+         +--------------------+
  1/2 cup|butter |         |cream butter        |
         +-------+         +--------------------+
    1 cup|sugar  |         |gradually, add sugar|
         +-------+         +--------------------+
        2|eggs   |         |break eggs          | 
         +-------+         +--------------------+
           ...                ...
                      ||
                      ||
                     \||/
                      \/
                   Program

C

• c is a procedural language. That means it emphasizes the algorithm side of programming.
• Conceptually, procedural programming consists of figuring out the actions a computer should take and then using the programming language to implement those actions.
• Top-down design: with c, the idea is to break a large program into smaller, more manageable tasks.
• If one of these tasks is still too broad, you divide it into yet smaller tasks.
• You continue with this process until the program is compartmentalized into small, easily programmed modules.
• C's design facilitates this approach, encouraging you to develop program units called functions to represent individual task modules.
• The C language incorporated features such as control structures and functions to better control the flow of a program and to enable a more structured, modular approach.

C++

• C++ adds object-oriented concepts to the C language.
• Unlike procedural programming, which emphasizes algorithms, OOP emphasizes the data.
• Rather than try to fit a problem to the procedural approach of a language, OOP attempts to fit the language to the problem.
• The idea is to design data forms that correspond to the essential features of a problem.
• In C++, a class is a specification describing such a new data form, and an object is a particular data structure constructed according to that plan.
• The process of going from a lower level of organization, such as classes, to a higher level, such as program design, is called bottom-up programming.
• OOP facilitates creating reusable code, and that can eventually save a lot of work.
• Information hiding safeguards data from improper access.
• Polymorphism lets you create multiple definitions for operators and functions, with the programming context determining which definition is used.
• Inheritance lets you derive new classes from old ones.
• Instead of concentrating on tasks, you concentrate on representing concepts.
• Instead of taking a top-down programming approach, you sometimes take a bottom-up approach.
• A computer program translates a real-life problem into a series of actions to be taken by a computer.
• The OOP aspect of C++ gives the language the ability to relate to concepts involved in the problem, and the C part of C++ gives the language the ability to get close to the hardware.

Programming steps

                   +-----------+
                   |source code|
                   +-----------+
                         |
                         v
                   +-----------+
                   |  COMPILER |
                   +-----------+
                         |
                         v
                   +-----------+
                   |object code|
                   +-----------+
                         |
 +------------+          |
 |startup code|          |
 +------------+          |
           |             v
           |-----> +-----------+
                   |   LINKER  |
           |-----> +-----------+
 +------------+          |
 |library code|          |
 +------------+          |
                         v
                   +---------------+
                   |executable code|
                   +---------------+

Compilation and Linking

• Originally, Bjarne Stroustrup implemented C++ with a C++-to-C compiler program instead of developing a direct C++-to-object code compiler.
• This program, called cfront (for C front end), translated C++ source code to C source code, which could then be compiled by a standard C compiler.
• As C++ has developed adn grown in popularity, more and more implementers have turned to creating C++ compliers that generate object code directly from C++ source code.
• This direct approach speeds up the compilation process and emphasizes that C++ is a separate, if similar, language.

Reference

• C++ Primer Plus (6th Edition) (Developer's Library) 6th Edition by Stephen Prata