Variables and Assignments

C# Tutorials - Herong's Tutorial Examples

∟Variables and Assignments - Example

This section provides a tutorial example on how to use variables, variable declaration statements, and assignment statements.

Now let's review what have learned in this section with a sample program:

// Variables.cs
// Copyright (c) 2006 HerongYang.com. All Rights Reserved.

class Variables {
   public static void Main() {
      bool is_ok;
      int n;
      int num_of_sec;
      long number_of_sec_in_a_year;
      float sqrt_s;
      double sqrt_d;
      char c1, c2, c3;
      char cr, cn;

      is_ok = true;
      num_of_sec = 86400;
      number_of_sec_in_a_year = 30458700;
      sqrt_s = 1.4142F;
      sqrt_d = 1.4142135623730950488016887242097;
      c1 = 'a';
      c2 = 'A';
      c3 = '0';
      cr = '\r';
      cn = '\n';

      n = 1;
      System.Console.WriteLine("Value of is_ok = {0}.", is_ok);
      System.Console.WriteLine("1 day = {0} seconds.", num_of_sec);
      System.Console.WriteLine("1 year = {0} seconds.",
         number_of_sec_in_a_year);
      System.Console.WriteLine(
         "Square root of 2 (float) = {0}.", sqrt_s);
      System.Console.WriteLine(
         "Square root of 2 (double) = {0}.", sqrt_d);
      System.Console.WriteLine(
         "Some regular characters: {0}, {1}, {2}.", c1, c2, c3);
      System.Console.WriteLine("The return character: {0}.", cr);
      System.Console.WriteLine("The new line character: {0}.", cn);
      n = 9;
      System.Console.WriteLine("WriteLine() is used {0} times.", n);
   }
}

Output of the program will be:

Value of is_ok = True.
1 day = 86400 seconds.
1 year = 30458700 seconds.
Square root of 2 (float) = 1.4142.
Square root of 2 (double) = 1.4142135623731.
Some regular characters: a, A, 0.
.he return character:
The new line character:
.
WriteLine() is used 9 times.

Observations from this program:

Suffix 'F' is used in literal "1.4142", because real literals are considered to be of 64-bit size, which requires variable type "double" to hold the value. The suffix 'F' is forcing a real literal to be of 32-bit size.
Literal "1.4142135623730950488016887242097" gets truncated and rounded to "1.4142135623731" during the execution of the assignment statement, because the double variable name sqrt_d can only hold about 14 decimal digits.
Variable "n" gets assigned twice in the program. Variables can be assigned to new values many times.

Advice: Avoid using "int" and "float". Use "long" and "double" instead. In the old days, 32-bit data requires less memory to store and computer time to process than 64-bit data. This is not totally true now, because today's computers are designed to store and process data 64 bits at a time, not 32 bits at a time.