Hello
World:
// File name: hello_world.cpp
// A simple C++ program which prints
"Hello World!" on the screen.
#include <iostream> // header file to support the C++ I/O
system.
using namespace std; // telling the compiler to use namespace
"std",
// where
the entire C++ library is declared.
int main() {
cout << "Hello World!"
<< endl;
/*
*
cout is the standard output
device on the screen.
*
<< causes the expression
on its right to be directed to the device on its left.
*
return 0; indicates the
successful termination of the "main" function.
*/
return 0;
}
Output:
Hello World!
Variables
And Constants:
// File name: variable.cpp
// Demonstrate the use of variables and
constants.
#include <iostream>
using namespace std;
const int CONST_VAL = 5; // declaring a
constant. Its value can't be changed.
int
iValue; // an integer variable
float
fValue; // a floating point
variable
char
cValue; // a character variable
iValue = 1234; // assigns 1234 to iValue
fValue = 1234.56; // assigns 1234.56 to
fValue
cValue = 'A'; // assigns A to cValue
//now print them out on the screen
cout << "Integer value is:
" << iValue << endl;
cout << "Float value is:
" << fValue << endl;
cout << "Character value is:
" << cValue << endl;
cout << "The constant is:
" << CONST_VAL << endl;
return 0;
}
Output:
Integer value is: 1234
Float value is: 1234.56
Character value is: A
The constant is: 5
Basic
Input/Output:
// File name: basicIO.cpp
// Convert gallons to liters.
#include <iostream>
using namespace std;
int main() {
float gallons, liters;
cout << "Enter number of
gallons: " << endl;
cin >> gallons; // Read the inputs
from the user
liters = gallons * 3.7854; // convert to
liters
cout << "Liters: "
<< liters << endl;
return 0;
}
Output:
Enter number of gallons: 14
Liters: 52.9956