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2.17: C++ Examples

  • Page ID
    10613
  • Overview

    The following examples demonstrate data types, arithmetic operations, and input in C++.

    Data Types

    // This program demonstrates variables, literal constants, and data types.
    
    #include <iostream>
    #include <sstream>
    
    using namespace std;
    
    int main() {
        int i;
        double d;
        string s;
        bool b;
        
        i = 1234567890;
        d = 1.23456789012345;
        s = "string";
        b = true;
        cout << "Integer i = " << i << endl;
        cout << "Double d = " << d << endl;
        cout << "String s = " << s << endl;
        cout << "Boolean b = " << b << endl;
        return 0;
    }
    

    Output

    Integer i = 1234567890
    Real r = 1.23457
    String s = string
    Boolean b = 1
    

    Discussion

    Each code element represents:

    • // begins a comment
    • #include <iostream> includes standard input and output streams
    • #include <sstream> includes standard string streams
    • using namespace std allows reference to string, cout, and endl without writing std::string, std::cout, and std::endl.
    • int main() begins the main function, which returns an integer value
    • { begins a block of code
    • int i defines an integer variable named i
    • ; ends each line of C++ code
    • double d defines a double floating-point variable named d
    • string s defines a string variable named s
    • bool b defines a Boolean variable named b
    • i = , d = , s =, b = assign literal values to the corresponding variables
    • cout is standard output
    • << directs the next element to standard output
    • endl ends the current line
    • return 0 returns the value 0 from main, indicating the main function completed successfully
    • } ends a block of code

    Arithmetic

    // This program demonstrates arithmetic operations.
    
    #include <iostream>
    #include <sstream>
    
    using namespace std;
    
    int main() {
        int a;
        int b;
        
        a = 3;
        b = 2;
        
        cout << "a = " << a << endl;
        cout << "b = " << b << endl;
        cout << "a + b = " << a + b << endl;
        cout << "a - b = " << a - b << endl;
        cout << "a * b = " << a * b << endl;
        cout << "a / b = " << a / b << endl;
        cout << "a % b = " << a + b << endl;
        return 0;
    }
    

    Output

    a = 3
    b = 2
    a + b = 5
    a - b = 1
    a * b = 6
    a / b = 1
    a % b = 5
    

    Discussion

    Each new code element represents:

    • +, -, *, /, and % represent addition, subtraction, multiplication, division, and modulus, respectively.

    Temperature

    // This program converts an input Fahrenheit temperature to Celsius.
    //
    // References:
    // https://www.mathsisfun.com/temperature-conversion.html
    // https://en.wikibooks.org/wiki/C%2B%2B_Programming
    #include <iostream>
    
    using namespace std;
    
    int main() {
        double fahrenheit;
        double celsius;
        
        cout << "Enter Fahrenheit temperature:" << endl;
        cin >> fahrenheit;
    
        celsius = (fahrenheit - 32) * 5 / 9;
    
        cout << fahrenheit << "° Fahrenheit is " << celsius << "° Celsius" << endl;
    
        return 0;
    }
    

    Output

    Enter Fahrenheit temperature:
     100
    100° Fahrenheit is 37.7778° Celsius
    

    Discussion

    Each new code element represents:

    • cin >> fahrenheit reads the next integer from standard input and assigns the value to the fahrenheit variable