// File name: HelloWorld.cpp // Purpose: A simple C++ program which prints "Hello World!" on the screen #include <iostream> // need this 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() { // Print out a sentence on the screen. // "<<" causes the expression on its right to // be directed to the device on its left. // "cout" is the standard output device -- the screen. cout << "Hello World!" << endl; return 0; // returns 0,which indicate the successful // termination of the "main" function }
mercury[24]% CC HelloWorld.cpp -LANG:std -o HelloWorld mercury[25]% HelloWorld Hello World! mercury[26]%
// File name: ~ftp/pub/class/cplusplus/HelloWorld/Variable.cpp // Purpose: Demonstrate the use of variables and constants // #include <iostream> using namespace std; // declaring a constant. It's value cannot be changed. const int CONST_VAL = 5; int main() { 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; }
mercury[39]% CC Variable.cpp -LANG:std -o Variable mercury[40]% Variable Integer value is: 1234 Float value is: 1234.56 Character value is: A The constant is: 5 mercury[41]%
// File name: ~ftp/pub/class/cplusplus/HelloWorld/BasicIO.cpp // Purpose: Converts gallons to liters #include <iostream> using namespace std; int main() { float gallons, liters; cout << "Enter number of gallons: "; cin >> gallons; // Read the inputs from the user liters = gallons * 3.7854; // convert to liters cout << "Liters: " << liters << endl; return 0; }
mercury[46]% CC BasicIO.cpp -LANG:std -o BasicIO mercury[47]% BasicIO Enter number of gallons: 14 Liters: 52.9956 mercury[48]%