Chapter P6. The C++ Language

Introduction

This is the chapter about C++ programming language. C++ is the right symbol to represent the extensions to the C language, as well a new level of data abstraction and an object level. The C++ language was invented by Dr. Bjarne Stroustrup with the publication of different articles from 1983, introduce in C, the concept of Class. The class facility is based on a similar facility available in Simula 67.

C++ is different than C.  C is a great programming language but C++ is better.

Without comparative adjectives, C++ is a powerful modern sucessor language to C.

In previous chapters we use the C Compiler or gcc (GNU C Compiler), in this chapter we need to move to c++ compiler.

[root@ftosx1 bin]# ls -al c++ g++
-rwxr-xr-x    4 root     root        80876 Jul 13 00:15 c++
-rwxr-xr-x    4 root     root        80876 Jul 13 00:15 g++
[root@ftosx1 bin]#

However, is not important to have a new extension, like "CC", "cpp", or "cxx"; the compiler will understand the source, also if we use the classical extension "c", for normal C source.

Therefore, we can have:

[root@ftosx1 The_C++_Programming_Language]# more hello_world.c
// The Hello world program.

// pg 46, sec 3.2, Hello, World!

// No guarantees offered. Constructive comments to bs@research.att.com
 
 

#include <iostream>

int main()
{
        std::cout << "Hello, world!\n";
}

// note that "return 0;" isn't required in ISO C++

[root@ftosx1 The_C++_Programming_Language]# g++ hello_world.c -o hello_world
[root@ftosx1 The_C++_Programming_Language]#
[root@ftosx1 The_C++_Programming_Language]# ./hello_world
Hello, world!
[root@ftosx1 The_C++_Programming_Language]#
 

Therefore is important to use the right compiler. The extension is superflous. The C++ inventor, Dr. Stroupstrup basically uses the "c" extension.

In C++ everything have a object-oriented perspective. For example in C++ is possible to "sum" strings.

Take for example the following example from Qt Manual.

Strings can be added to a list using append(), operator+=() or operator<<(), e.g.

    QStringList fonts;
    fonts.append( "Times" );
    fonts += "Courier";
    fonts += "Courier New";
    fonts << "Helvetica [Cronyx]" << "Helvetica [Adobe]";

String lists have an iterator, QStringList::Iterator(), e.g.

    for ( QStringList::Iterator it = fonts.begin(); it != fonts.end(); ++it ) {
        cout << *it << ":";
    }
    cout << endl;
    // Output:
    //  Times:Courier:Courier New:Helvetica [Cronyx]:Helvetica [Adobe]:
 

Therefore, we can "add" strings, as numbers. The "magic" is not fact, the sucessfull is the abstract different data types (strings and numbers), and use them without to play attention to the role.

It is possible to extend a function to a new function using the parameters of the old function.

For example, a C++ declaration may be as follows:

 const QMimeSource *m = QMimeSourceFactory::defaultFactory()->data( name );

Basically, we can create or re-use old objects with new ones;

C++ is available from 1985 (first edition of Bjarne Stroupstrup: The C++ Programming Language, now in its available is third edition, 1998), however important projects like GNOME are completely developed in C, instead of C++. This explain how C++ may be complex for a beginner, or basically may requery some level of abstraction and debugging that not necessarily is reached immediately.

However the sucessfull Qt and KDE projects are completely written in C++.

C++ is a new dimension ... a new planet in the mind. It is really interesting and beautifull from a esthetic designer point of view.

Are you ready ?

The C++ Implementation

• They must be understand how C++ is different from C, and
• They must know how to implement the C++ concepts, using the new operators.

A new mode to include files

Before we start to code in C++ is important to know that from the 1983 until nowadays, the C++ changes and fix different standards. A major upgrade happens from version 2 to version 3 (actual). Actual version, called "version 3" is the ISO C++.

For example if we includes the .h we will get some minor errors because actually are not used anymore. These version are created by the C++ designer, Dr. Stroustrup.

Basically the "The C++ Programming Language - Third Edition" fix the new standard.

This is an example, about what happen if we includes includes files, with ".h".

[root@ftosx1 Chap6]# more example.cpp
#include <iostream.h>
#include <string.h>

using namespace std;

int main()
{
     string s;
     cout << "Please enter your first name followed by a newline\n";
     cin >> s;
     cout << "Hello, " << s << '\n';
     return 0; // this return statement isn't necessary
}
[root@ftosx1 Chap6]#
 

[root@ftosx1 Chap6]# g++ example.cpp -o example
In file included from /usr/include/g++-v3/backward/iostream.h:31,
                 from example.cpp:1:
/usr/include/g++-v3/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header. Please consider using one of the 32 headers found in section 17.4.1.2 of the C++ standard. Examples include substituting the <X> header for the <X.h> header for C++ includes, or <sstream> instead of the deprecated header <strstream.h>. To disable this warning use -Wno-deprecated.
[root@ftosx1 Chap6]#
 

The correct mode is as follows:

[root@ftosx1 Chap6]# more example.cpp
#include <iostream>
#include <string>

using namespace std;

int main()
{
     string s;
     cout << "Please enter your first name followed by a newline\n";
     cin >> s;
     cout << "Hello, " << s << '\n';
     return 0; // this return statement isn't necessary
}
[root@ftosx1 Chap6]#
 

The result is quite simple.

[root@ftosx1 Chap6]# g++ example.cpp -o example
[root@ftosx1 Chap6]# ./example
Please enter your first name followed by a newline
Giovanni A. Orlando
Hello, Giovanni
[root@ftosx1 Chap6]#
[root@ftosx1 Chap6]#

Note that we use the "namespace" std; that stand for standard. If we don't want to use this namespace (or convention) we need to add the word: "std" as a prefix on any used function.

For example, the previous code will works also as follows:

[root@ftosx1 Chap6]# more example2.cpp
#include <iostream>
#include <string>

//using namespace std;

int main()
{
        std:: string s;
        std::cout << "Please enter your first name followed by a newline\n";
        std::cin >> s;
        std::cout << "Hello, " << s << '\n';
     return 0; // this return statement isn't necessary
}
[root@ftosx1 Chap6]#

Compiling we will get the same result.

[root@ftosx1 Chap6]# ./example
Please enter your first name followed by a newline
Giovanni
Hello, Giovanni
[root@ftosx1 Chap6]#

Therefore using the "namespace" will save time and the code will be more simple. However, we can also mix C includes with C++ includes. In this case, is fundamental to avoid namespace and add the prefix representing in full each declaration.
 

New Operators for Standard I/O.

In C++,  are present some new interesting operators from the simple standard Input to get characters from the keyboard, or to print variables, up to use functions as a member of class.

For example, in the previous example, suppose you want to print a program to transform dollars to euro .

In C++, we use the cout and cin operators for I/O.

Therefore as a preliminary program, we test I/O from the keyboard.

Our first example, will input a quantity in dollar and will print the output in euro.

[root@ftosx1 Chap6]# more dollar2euro.cpp

#include <iostream.h>

main ()
{
        double mydollar;

        cout << "\nInput dollar quantity:";

        cin >> mydollar;

        cout << "\nYou input\n" << mydollar << endl;

}
[root@ftosx1 Chap6]#

[root@ftosx1 Chap6]# c++ dollar2euro.cpp -o dollar2euro
[root@ftosx1 Chap6]# ./dollar2euro

Input dollar quantity:50

You input
50
[root@ftosx1 Chap6]#

cout is the C++ operator to print variables, while cin is the input operator.

The US$ - Euro rate changes at any moment. At the moment this chapter was developed, the rate is:

    1 US Dollar =  0.99661 Euro

at http://www.oanda.com/convert/classic

Therefore, we update the source to do the math:

[root@ftosx1 Chap6]# more dollar2euro.cpp

#include <iostream>

using namespace std;

main ()
{
        double mydollar;

        cout << "\nInput dollar quantity:";

        cin >> mydollar;

        cout << mydollar << " US$ are " << mydollar*0.99661 << " euros" << endl;

}
[root@ftosx1 Chap6]#

Note here that this is extremely easy.
 

What is a Class ?

The class is the most used C++ concept

Suppose that in C you are working with a simple C structure books.

[root@ftosx1 Chap6]# more books1.c
/*****
* File:         books.cpp
* Description:  C motivation for classes
*
******/
 

typedef struct _book {
   char      title[30];
   char      author[30];
   char      editorial[30];
   int       book_id;
   int       publication_year;
} book;
 

void book_print(book  *mylocalbook );
void insert_book (char *mytitle, char * myauthor, char * myeditorial, int mybook_id, int mypublication_year );

void insert_book (char *mytitle, char * myauthor, char * myeditorial, int mybook_id, int mypublication_year )
{

   book mybook;

   strcpy(mybook.title, mytitle);
   strcpy(mybook.author, myauthor);
   strcpy(mybook.editorial, myeditorial);

   mybook.book_id = mybook_id;
   mybook.publication_year = mypublication_year;

   book_print( &mybook);
}

void book_print(book  *mylocalbook )
{
 

   printf ("%s %s %s %d %d\n", mylocalbook->title, mylocalbook->author, mylocalbook->editorial,
                               mylocalbook->book_id, mylocalbook->publication_year);

}

main()
{

   puts ("\nSome C and C++ books:\n");

   insert_book ("C++ & C Tools", "David Spuler", "Prentice Hall PTR", 20, 1988);
 

   exit (0);

}

This example, works fine:

[root@ftosx1 Chap6]# make books1
cc     books1.c   -o books1
[root@ftosx1 Chap6]# ./books1

Some C and C++ books:

C++ & C Tools David Spuler Prentice Hall PTR 20 1988
[root@ftosx1 Chap6]#

The Stroupstrup idea was to join the functions ... inside the structure and create the necessary enviroment to work!. This kind of geniality, generally changes things for ever.

Therefore now we motivate a class!

A valid C++ class may be as follows

class book {
private:
   char      title[30];
   char      author[30];
   char      editorial[30];
   int       book_id;
   int       publication_year;
public:
   book(char * mytitle, char *myauthor, char * myeditorial, int mybook_id, int mypublication_year );
   void  print();
};

Note that we includes the function inside the class. This is one of the C++ enhancements.

Now, when we write

s1  book         s1("C++ & C Tools", "David Spuler", "Prentice Hall PTR", 91, 1996);

and

s1.print ();

We are calling a class component that is a function.

We also add and declare some members public and other private. This is a second C++ enhacements.

Now, we will create a C++ version with classes, based on the previous C example, based on structures.

We present here a numbered version and explain important points.

      1 /*****
      2 * File:         books.cpp
      3 * Description:  Introduce classes and derived classes
      4 *
      5 ******/
      6
      7 #include <iostream>
      8 #include <string>
      9
     10 using namespace std;
     11
     12 class book {
     13 private:
     14    char      title[30];
     15    char      author[30];
     16    char      editorial[30];
     17    int       book_id;
     18    int       publication_year;
     19 public:
     20    book(char * mytitle, char *myauthor, char * myeditorial, int mybook_id, int mypublication_year );
     21    void  print();
     22 };
     23
     24 book::book(char *mytitle, char * myauthor, char * myeditorial, int mybook_id, int mypublication_year )
     25 {
     26    strcpy(title, mytitle);
     27    strcpy(author, myauthor);
     28    strcpy(editorial, myeditorial);
     29
     30    book_id = mybook_id;
     31    publication_year = mypublication_year;
     32 }
     33
     34 void book::print()
     35 {
     36     cout << author << title << ", " << book_id << ", "
     37          << publication_year << "-" << editorial << endl;
     38 }
     39
     40 main()
     41 {
     42    book         s1("C++ & C Tools", "David Spuler", "Prentice Hall PTR", 91, 1996);
     43    book         s2("The C++ Programming Language", "Bjarne Stroustup", "Addison Wesley", 90, 1998);
     44    book         s3("The C Programming Language", "Brian W. Kernigham and Dennis M. Ritchie", "Prentice Hall PTR", 20, 1988);
     45
     46
     47    cout << "\nSome C and C++ books:\n";
     48
     49    s1.print();
     50    s2.print();
     51    s3.print();
     52 }
     53
 

Here we define books like function with the same class. This choice is called constructor. Therefore a constructor is a member function whose name is the same as the class name.

In the previous example the constructor is: book

Declared inside the class

book(char * mytitle, char *myauthor, char * myeditorial, int mybook_id, int mypublication_year );

... and defined later

book::book(char *mytitle, char * myauthor, char * myeditorial, int mybook_id, int mypublication_year )
{
   strcpy(title, mytitle);
   strcpy(author, myauthor);
   strcpy(editorial, myeditorial);

    book_id = mybook_id;
    publication_year = mypublication_year;
}

book::print is a simple member of the class book.

To explain the previous source we can said the following:

• In the main(), we define different books using the constructor.
• We print a message with cout ... and
• We print the content of any book

[root@ftosx1 Chap6]# c++ books1.cpp -o books1
[root@ftosx1 Chap6]# ./books1

Some C and C++ books:
David SpulerC++ & C Tools, 91, 1996-Prentice Hall PTR
Bjarne StroustupThe C++ Programming Language, 90, 1998-Addison Wesley
Brian W. Kernigham and Dennis Prentice Hall PTRThe C Programming Language, 20, 1988-Prentice Hall PTR
[root@ftosx1 Chap6]#

Now, we will explain some other examples about classes.

Another clear and elementary example about classes may be introduced working with complex numbers.

C++ offers these classes in the standard C++ Library.

Now, we will start with a simple example:

We suppose here that complex have a full implementation in C++, but this is not the case. Only a mininal implementation is provided, basically like "empty" objects where we can arrange our code.

[root@ftosx1 Chap6]# more complex.cpp
 

#include <complex>
#include <iostream>

using namespace std;

main ()
{
    complex< float >  ld = (5.0,8.23) ;

    complex< double > lc1 = -3.0 ;

    complex< double>  lc = (5.1,8.23) ;

    cout << ld << endl;
    cout << lc << endl;

    cout << "The real part of ld is " << ld.real() << endl;
    cout << "The imaginary part of ld is " << ld.imag() << endl;
 

    cout << "The imaginary part of ld now is " << ld.imag() << endl;

}
[root@ftosx1 Chap6]#
 

Compiling and running we will have:
 

[root@ftosx1 Chap6]# g++ complex.cpp -o complex
[root@ftosx1 Chap6]# ./complex
(8.23,0)
(8.23,0)
The real part of ld is 8.23
The imaginary part of ld is 0
The imaginary part of ld now is 0
[root@ftosx1 Chap6]#
 

Note that neither the imaginary part is provided as a result.

A better implementation is made by the Dr. Stroupstroup:
[root@ftosx1 Chap6]# vi complex_out2.c

[root@ftosx1 Chap6]# more complex_out2.c

#include<iostream>

using namespace std;
 

// Note: my "complex"; not the one from the standard library

class complex {
public:
        complex(double r =0, double i =0) : re(r), im(i) { }

        double real() const { return re; }
        double imag() const { return im; }
        // ...
private:
        double re, im;
};

ostream& operator<<(ostream&s, const complex& z)
{
        return s << '(' << z.real() << ',' << z.imag() << ')';
}
 

int main()
{
        complex x1(1,2);
        complex x2(0.33,2.54);

        cout << "x1 = " << x1 << '\n';
        cout << "x2 = " << x2 << '\n';

        return 0;       // redundant in ISO C++
}
[root@ftosx1 Chap6]#
 

[root@ftosx1 Chap6]# ./complex_out
x = (1,2)
[root@ftosx1 Chap6]#
 

Basically, we here had been re-written the "<<" operator for complex numbers!
 

What we need to do if we want to get the "sum" of complex numbers, like we know from Mathematics ?

Easy, we need to overload the + operator.

/**********************************************************************
  Filename:  complex3.cpp

  Chapter:   1      Overview of C++ and Object Oriented Programming

  Compiler:  Borland C++     Version 5.01      Summer 1998

  C++ for C Programmers, Edition 3     By Ira Pohl

********************************************************************/
 

#include <iostream>      //IO library
#include <string>        //string type
 

using namespace std;

 //An elementary implementation of type complex
 

class complex {

public:                   //universal access to interface

   //constructor

   complex(double r=0, double im=0): real(r), imaginary(im) { }

   //destructor

   ~complex() { cout << "destructor called on "; print(); }

   void re_assign(double r) { real = r; }

   void im_assign(double im) { imaginary = im; }

   void print() const

      { cout << "(" << real << "," << imaginary << "i)" << endl; }

   void  print(string var_name) const

      { cout << var_name << " = "; print(); }

   friend complex operator+(complex, complex);

private:                  //restricted access to implementation

   double real, imaginary;

};
 

//overload +

complex operator+(complex x, complex y)
{
   complex t;

   t.real = x.real + y.real;
   t.imaginary = x.imaginary + y.imaginary;

   return t;
}

int main()

{
   complex x(9.5, -4.5), y(4.2,6.0), z;

   z = x + y;

   x.print("x");

   y.print("y");

   z.print("z");

   int look; cin >> look;

}

Here we will get our expectations:

[root@ftosx1 Chap6]# ./complex3
destructor called on (13.7,1.5i)
destructor called on (9.5,-4.5i)
destructor called on (4.2,6i)
x = (9.5,-4.5i)
y = (4.2,6i)
z = (13.7,1.5i)

Note that we here re-define the "+" operator.

This process is called "overloading" the operator. It is a basic technique in C++ programming. Originally the complex operator "+", is incomplete ... or expect to be overloaded for a full usage.

There are differet C++ compilers. We now list different:

• GNU GCC, actually 3.1
• Intel C++ Compiler, actually 6.1
• Apple C++ Compiler
• Microsoft C++ Compiler
• Borland C++ Compiler

Constructors and Destructors

class complex {

public:                   //universal access to interface

   //constructor

   complex(double r=0, double im=0): real(r), imaginary(im) { }

   //destructor

   ~complex() { cout << "destructor called on "; print(); }

   void re_assign(double r) { real = r; }

   void im_assign(double im) { imaginary = im; }

   void print() const

      { cout << "(" << real << "," << imaginary << "i)" << endl; }

   void  print(string var_name) const

      { cout << var_name << " = "; print(); }

   friend complex operator+(complex, complex);

private:                  //restricted access to implementation

   double real, imaginary;

};

If we comment the line:   " //int look; cin >> look;"

we will get a new output including the destructor call

[root@ftosx1 Chap6]# ./complex3
destructor called on (13.7,1.5i)
destructor called on (9.5,-4.5i)
destructor called on (4.2,6i)
x = (9.5,-4.5i)
y = (4.2,6i)
z = (13.7,1.5i)
destructor called on (13.7,1.5i)
destructor called on (4.2,6i)
destructor called on (9.5,-4.5i)
[root@ftosx1 Chap6]#
 

Therefore, basically we are adding or allocating information when we add (or use the constructor) and this info will be free when we call the destructor.

Would our program works if we comment the destructor ? Why ?

The example we introduce before may be applied to any class.

For example, working with strings we will have:

[root@ftosx1 Chap6]# more string1.cpp

#include <iostream>
#include <string>

using namespace std;

int main()
{
      cout << "Please enter a line:\n";

      string s;
      getline(cin,s);
 

     cout << "You entered " << s << '\n';

}
[root@ftosx1 Chap6]# g++ string1.cpp -o string1
[root@ftosx1 Chap6]# ./string
Please enter a line:
FTLinuxCourse covers C++
You entered FTLinuxCourse covers C++
[root@ftosx1 Chap6]#

I prefer you investigate yourself on strings in C++.

File I/O

Basically, it uses the "fstream" include to open/close/read streams.

We list now a

[root@ftosx1 Chap6]# more read_complex_numbers.cpp
/* Code for exercise 21.1.
 |
 | "C++ Solutions--Companion to The C++ Programming Language, Third Edition"
 | by David Vandevoorde; Addison-Wesley 1998; ISBN 0-201-30965-3.
 |
 | Permission to use, copy, modify, distribute and sell this software
 | and its documentation for any purpose is hereby granted without fee.
 | The author makes no representations about the suitability of this
 | software for any purpose.  It is provided "as is" without express or
 | implied warranty.
 `----------------------------------------------------------------------*/

#include <complex>
#include <fstream>
#include <iostream>
#include <stdlib.h>

void error(char const *prog, char const *entity,
           char const *msg) {
   std::cerr << prog << ": " << entity << msg << '\n';
   exit(1);
}

int main(int argc, char *argv[]) {
   if (argc!=2)
      error(argv[0], "", ": unexpected number of arguments.");
   std::ifstream numbers(argv[1]);
   if (!numbers)
      error(argv[0], argv[1], ": cannot open file for reading.");
   double re, im;
   while (numbers >> re) {
      if (numbers >> im)
         std::cout << std::complex<double>(re, im) << '\n';
      else
         std::cout << std::complex<double>(re, 0.0)
                   << "\nWarning: odd number of values.\n";
   }
   return 0;
}

[root@ftosx1 Ch21]#

Compiling and reading we will get:

[root@ftosx1 Chap6]# g++ read_complex_numbers.cpp -o read_complex_numbers
[root@ftosx1 Chap6]# ./read_complex_numbers complex_numbers
(1,1.2)
(-1.1,-0.3)
(0.5,0.5)
(-0.1,0)
Warning: odd number of values.
[root@ftosx1 Chap6]#

Therefore, in C++ the process to open/read and close the file is made in the line:

  std::ifstream numbers(argv[1]);

Similar process may be applied on files.

What does the "numbers" function ?

Please note that the previous example mix C and C++ include files.

Inheritance or Derived Classes

One of the most innovative concept that C++ introduce is the "Derived Classes" concept.

This means that a class may generate a new class, where the elements of the "father" class will be inherited by the new class.

An immediate and simple example, is the following:

Let be a class called student.

classs student {
public:
    int student_id;
    float grade;
    char name[45];
    char address[90];
    enum {fresh, soph, junior, senior} year;
    char major[10];
    void print();
}

Then the "child" class; in C++ terms is called derived class will be:

classs graduate_student::public student {
public:
    enum {ta, ra, fellowship, other} support;
    char dept[15];
    char thesis [100];
    void print();
}

Any member of the first class will belong to the new class. This is the concept of derived (or inheritance).

So, the   int student_id, grade, name, address, year, major and print() are inherited.

C++ uses the keywords: public, private and protected to access visibility to a specific member in the class.

A member function defined within the class definition (in other words, not simple declared there), is taken to be an inline member function.

So, using inline we may change a class as follows:

class Date {
 public:
        int day(), const {return};
        // ...
private:
    int d, m, y;
}

Using inline we will simplify the previous class declaration.

class Date {
 public:
        int day() const;
        // ...
private:
    int d, m, y;
}
inline int Date::day() const {return d;}
 

The C++ Standard Library

In the same that in C we have our standard library, also C++ includes its standard library.

Basically, the use of "namespace std" fix to apply the standard library includes and keywords, without others. Without this declaration, will be necessary to add the prefix: "std::XXX" to each variable.

The C++ library are

[root@ftosx1 Chap6]# ls -F /usr/include/g++-v3/
algorithm  cctype   clocale  cstdarg  ctime     exception            i386-ftosx-linux/  istream   map      queue      streambuf  vector
backward/  cerrno   cmath    cstddef  cwchar    exception_defines.h  iomanip            iterator  memory   set        string
bits/      cfloat   complex  cstdio   cwctype   ext/                 ios                limits    new      sstream    typeinfo
bitset     ciso646  csetjmp  cstdlib  cxxabi.h  fstream              iosfwd             list      numeric  stack      utility
cassert    climits  csignal  cstring  deque     functional           iostream           locale    ostream  stdexcept  valarray
[root@ftosx1 Chap6]#

We complete this chapter with a simple example about strings:

[root@ftosx1 Chap6]# more string2.cpp

#include <iostream>
#include <string>

using namespace std;

int main()
{
     string s1 = "Hello";
     string s2 = "World";

         string s3 = s1 + "," + s2 + "\n";
     cout << s3 ;

}
[root@ftosx1 Chap6]#

Compiling and running we will have:

[root@ftosx1 Chap6]# g++ string2.cpp -o string2
[root@ftosx1 Chap6]# ./string2
Hello,World
[root@ftosx1 Chap6]#
 

What is the C++ Library, as Linux library ?

C++ Keywords

Conclusions

Do you like C++?

C++ is really a great language and a valid C extension. Working with classes and in a Object-Oriented Programming (OOP) is more interesting that on the classic C.

The book "The C++ Programming Language"  - 3rd edition written by Bjarne Stroustrup, includes 911 pages. However, in this chapter we resume the most important concepts to get started and start to code. The most significative elements in C++ programming are covered.

Basically, no other reading is necessary. Both the code for this books and its companion: "The C++ Solution" by David Vandevoorde offers a sufficient material for a preliminary further reading.

A latest source is "C for C++ Programmers" by Ira Pohl (Only strange names between C++ authors).

Will be the daily KDE, Qt or C++ code to complete the C++ education.
 

Exercises

1. Download a KDE example and try to understand what are the classes

Test

1. Who was the C++ inventor ?
2. How is the correct mode to includes files in C++ programs ?
3. What means "namespace" ?
4. What means "using namespace std" ? Why is important ?
5. Is possible to write C++ code that includes C include files ?
6. What is a Class?
7. Is necessary that C++ programs have a "cpp" extension is also "c" extension will work ?
8. What means operator overloading ?
9. How we add comments in C++ source ? Would be possible to use it also in C code ?
10. Is possible to use structures in C++ ?
11. Is possible to "add" strings as numbers in C++?  Why now is possible ?
12. What is this pointer ?
13. What is the name of the GNU C++ compiler ?
14. When you compile a C++ program and use a normal C function like "isalpha" or "fopen" ... are you using C #includes or C++ #includes ?
15. Where are located the includes files for the C++ compiler ?
16. What is a constructor ?
17. What is a destructor ?
18. The C++ operator cout is used with << or with >> ?
19. What is a template ?
20. What means inline ?
21. What is the C++ Standard Library ?
22. List five include files that end with "stream" ?
23. Would be possible to use Complex numbers (a+ib) with the standard library ?
24. Would be possible to work with Complex number in C++ problems ... or we will need to re-implement ?
25. Is possible that a derived class become a base class ?
26. What is the heap ?
27. Would be possible to debug C++ programs ?
28. What means "book:book" ?
29. List four C++ Compilers ?
30. What is the language used by OpenOffice (FTOffice) ?
31. In what language was developed the Troll Qt libraries ?
32. In what language was developed Motif ?
33. Why C++ is a better language for the development of graphical interfaces ?
34. When was C++ invented ?
35. What means "this" in the following expression ?

  template<typename _Tp>
    inline complex<double>&
    complex<double>::operator+=(const complex<_Tp>& __z)
    {
      __real__ _M_value += __z.real();
      __imag__ _M_value += __z.imag();
      return *this;
    }

Consult the answers

Check the Interactive Exam Cram Programming: 

Internet Resources for this Chapter.

• Bjarne Stroustrup Web pages
• C++ Glossary
• C++ FAQ
• C++ Source Code(also locally)
• Open issues for The C++ Programming Language (3rd Edition)
• Chaos Classes
• GCC Home Page
• http://gcc.gnu.org/libstdc++/