Victor's CS Site [ COP3014 ]

Fundamental data types are basic types implemented directly by the language that represent the basic storage units supported natively by most systems. They can mainly be classified into:

• Character types: They can represent a single character, such as 'A' or '$'. The most basic type is char, which is a one-byte character.
• Numerical integer types: They can store a whole number value, such as 7 or 1024. They exist in a variety of sizes, and can either be signed or unsigned, depending on whether they support negative values or not.
• Floating-point types: They can represent real values, such as 3.14 or 0.01, with different levels of precision, depending on which of the three floating-point types is used.
• Boolean type: The boolean type, known in C++ as bool, can only represent one of two states, true or false.

The include directive instructs the preprocessor to paste the text of the given file into the current file.

So a #include <stdio.h> statement will be replaced by the contents of stdio.h.

The main() function.

When the operating system runs a program in C/C++, it passes control of the computer over to that program. The key point is that the operating system needs to know where inside your program the control needs to be passed. In the case of a C/C++ language program, it’s the main() function that the operating system is looking for.

		#include <iostream>

		int main()
		{
		  std::cout << "Hello World!";

		  return 0;
		}
		

All the elements in the standard C++ library are declared within what is a called a namespace: the namespace std.

The using namespace std; declaration allows all elements in the std namespace to be accessed in an unqualified manner (without the std:: prefix).

Constants are expressions with a fixed value.

Constants are declared with the const keyword:

		const double pi = 3.1415926;
		const char tab = '\t';
		

Literals are the most obvious kind of constants. They are used to express particular values within the source code of a program.

Literals include integer numerals, floating-point numerals, characters, and strings.

#define identifier replacement

After this directive, any occurrence of identifier in the code is interpreted as replacement, where replacement is any sequence of characters (until the end of the line). This replacement is performed by the preprocessor, and happens before the program is compiled.

This operator accepts one parameter, which can be either a type or a variable, and returns the size in bytes of that type or object:

		int x = sizeof(char);
		

The assignment operator assigns a value to a variable.

		int x = 5; // assigns the value 5 to x
		

The equality operator tests if two values are equal and returns true or false.

		if( 7 == 5 ) // evaluates to false
		

		#include <iostream>
		using namespace std;

		int main ()
		{
		  int i;

		  cout << "Please enter an integer value: ";
		  cin >> i;
		  cout << "The value you entered is " << i;
		  cout << " and its double is " << i*2 << ".\n";

		  return 0;
	  	}
		

		#include <iostream>
		#include <string>
		using namespace std;

		int main ()
		{
		  string mystr;

		  cout << "What's your name? ";
		  getline (cin, mystr);
		  cout << "Hello " << mystr << ".\n";

		  return 0;
		}
		

		#include <iostream>
		using namespace std;

		int main ()
		{
		  int x;

		  cout << "Please enter an integer value:";
		  cin >> x;

		  if (x > 0)
		    cout << "x is positive";
		  else if (x < 0)
		    cout << "x is negative";
		  else
		    cout << "x is 0";

		  return 0;
		}
		

		#include <iostream>
		using namespace std;

		int main ()
		{
		  int n = 10;

		  while (n>0)
		  {
		     cout << n << ", ";
	             --n;
		  }
		  cout << n;

		  return 0;
		}
		

		#include <iostream>
		using namespace std;

		int main ()
		{
		  int n = 10;

		  for (int n=10; n>0; n--)
		     cout << n << ", ";

		  cout << n;

		  return 0;
		}
		

break leaves a loop, even if the condition for its end is not fulfilled. It can be used to end an infinite loop, or to force it to end before its natural end.

The continue statement causes the program to skip the rest of the loop in the current iteration, as if the end of the statement block had been reached, causing it to jump to the start of the following iteration.

		#include <iostream>
		using namespace std;

		int addition (int a, int b)
		{
		  return a+b;
		}

		int main ()
		{
		  int z;
		  z = addition (5,3);
		  cout << "The result is " << z;

		  return 0;
		}
		

		#include <iostream>
		using namespace std;

		int main ()
		{
		  int foo [] = {16, 2, 77, 40, 12071};
		  int n, result=0;

		  for ( n=0 ; n<5 ; ++n )
		     result += foo[n];

		  cout << result;

		  return 0;
		}
		

		#include <iostream>
		#include <string>
		using namespace std;

		struct movies_t {
		  string title;
		  int year;
		} the_movie;

		int main ()
		{
		  getline (cin,the_movie.title);
		  cout << "Enter year: ";
		  getline (cin,mystr);
		  stringstream(mystr) >> the_movie.year;

		  return 0;
		}
		

		#include <iostream>
		using namespace std;

		int main ()
		{

		  int firstvalue = 5, secondvalue = 15;
		  int * p1, * p2;

		  p1 = &firstvalue;  // p1 = address of firstvalue
		  p2 = &secondvalue; // p2 = address of secondvalue
		  *p1 = 10;          // firstvalue = 10
		  *p2 = *p1;         // secondvalue = 10
		  p1 = p2;           // p1 = p2 (value of pointer is copied)
		  *p1 = 20;          // secondvalue = 20

		  cout << "firstvalue is " << firstvalue << '\n';
		  cout << "secondvalue is " << secondvalue << '\n';

		  return 0;
		}

		This program outputs:
				firstvalue is 10
				secondvalue is 20