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52 lines
1.9 KiB
C#
52 lines
1.9 KiB
C#
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using System.Xml;
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object height = 1.88; // storing a double in an object
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object name = "Amir"; // storing a string in an object
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Console.WriteLine($"{name} is {height} metres tall.");
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//int length1 = name.Length; // gives compile error!
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int length2 = ((string)name).Length; // tell compiler it is a string
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Console.WriteLine($"{name} has {length2} characters.");
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// storing a string in a dynamic object
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// string has a Length property
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dynamic something = "Ahmed";
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// int does not have a Length property
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something = 12;
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// an array of any type has a Length property
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something = new[] { 3, 5, 7 };
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// this compiles but would throw an exception at run-time
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// if you later store a data type that does not have a
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// property named Length
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Console.WriteLine($"Length is {something.Length}");
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var population = 66_000_000; // 66 million in UK
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var weight = 1.88; // in kilograms
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var price = 4.99M; // in pounds sterling
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var fruit = "Apples"; // strings use double-quotes
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var letter = 'Z'; // chars use single-quotes
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var happy = true; // Booleans have value of true or false
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// good use of var because it avoids the repeated type
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// as shown in the more verbose second statement
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var xml1 = new XmlDocument(); // C# 3 and later
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XmlDocument xml2 = new XmlDocument(); // all C# versions
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// bad use of var because we cannot tell the type, so we
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// should use a specific type declaration as shown in
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// the second statement
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var file1 = File.CreateText("something1.txt");
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StreamWriter file2 = File.CreateText("something2.txt");
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Console.WriteLine($"default(int) = {default(int)}");
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Console.WriteLine($"default(bool) = {default(bool)}");
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Console.WriteLine($"default(DateTime) = {default(DateTime)}");
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Console.WriteLine($"default(string) = {default(string)}");
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int number = 13;
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Console.WriteLine($"number has been set to: {number}");
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number = default;
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Console.WriteLine($"number has been reset to its default: {number}");
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