< Programming Fundamentals

Overview

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

Data Types

// This program demonstrates variables, literal constants, and data types.

using System;

public class DataTypes
{
    public static void Main(string[] args)
    {
        int i;
        double d;
        string s;
        Boolean b;
        
        i = 1234567890;
        d = 1.23456789012345;
        s = "string";
        b = true;

        Console.WriteLine("Integer i = " + i);
        Console.WriteLine("Double d = " + d);
        Console.WriteLine("String s = " + s);
        Console.WriteLine("Boolean b = " + b);
    }
}

Output

Integer i = 1234567890
Double d = 1.23456789012345
String s = string
Boolean b = True

Discussion

Each code element represents:

  • // begins a comment
  • using System allows references to Boolean and Console without writing System.Boolean and System.Console
  • public class DataTypes begins the Data Types program
  • { begins a block of code
  • public static void Main() begins the main function
  • 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
  • Boolean b defines a Boolean variable named b
  • i = , d = , s =, b = assign literal values to the corresponding variables
  • Console.WriteLine() calls the standard output write line function
  • } ends a block of code

Arithmetic

// This program demonstrates arithmetic operations.

using System;

public class Arithmetic
{
    public static void Main(string[] args)
    {
        int a;
        int b;
        
        a = 3;
        b = 2;

        Console.WriteLine("a = " + a);
        Console.WriteLine("b = " + b);
        Console.WriteLine("a + b = " + (a + b));
        Console.WriteLine("a - b = " + (a - b));
        Console.WriteLine("a * b = " + a * b);
        Console.WriteLine("a / b = " + a / b);
        Console.WriteLine("a % b = " + (a + b));
    }
}

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.

using System;

public class Temperature
{
    public static void Main(string[] args)
    {
        double fahrenheit;
        double celsius;
        
        Console.WriteLine("Enter Fahrenheit temperature:");
        fahrenheit = Convert.ToDouble(Console.ReadLine());

        celsius = (fahrenheit - 32) * 5 / 9;

        Console.WriteLine(
            fahrenheit.ToString() + "° Fahrenheit is " + 
            celsius.ToString() + "° Celsius" + "\n");
    }
}

Output

Enter Fahrenheit temperature:
 100
100° Fahrenheit is 37.7777777777778° Celsius

Discussion

Each new code element represents:

  • Console.ReadLine() reads the next line from standard input
  • Convert.ToDouble converts the input to a double floating-point value

References

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