added answer files for C# Strings exercises

Author: alexoah

W3School-CSExercises/CS-Strings/csStringsE1.cs

@@ -0,0 +1,10 @@
+/**
+ *	from C# Strings: Exercise 1 ( https://www.w3schools.com/cs/exercise.asp?filename=exercise_strings1 )
+ *
+ *	question:
+ *	Fill in the missing part to create a greeting variable of type string and assign it the value Hello.
+ *
+ *	______ ________ = _______;
+ *
+ */
+string greeting = "Hello";

W3School-CSExercises/CS-Strings/csStringsE2.cs

@@ -0,0 +1,16 @@
+/**
+ *	from C# Strings: Exercise 2 ( https://www.w3schools.com/cs/exercise.asp?filename=exercise_strings2 )
+ *
+ *	question:
+ *	Use the correct operator to concatenate two strings:
+ *
+ *	string firstName = "John ";
+ *	string lastName = "Doe";
+ *	string name = firstName _ lastName;
+ *	Console.WriteLine(name);
+ *
+ */
+string firstName = "John ";
+string lastName = "Doe";
+string name = firstName + lastName;
+Console.WriteLine(name);

W3School-CSExercises/CS-Strings/csStringsE3.cs

@@ -0,0 +1,16 @@
+/**
+ *	from C# Strings: Exercise 3 ( https://www.w3schools.com/cs/exercise.asp?filename=exercise_strings3 )
+ *
+ *	question:
+ *	Use the string interpolation method to concatenate two strings:
+ *
+ *	string firstName = "John";
+ *	string lastName = "Doe";
+ *	string name = _"My full name is: ___________ __________";
+ *	Console.WriteLine(name);
+ *
+ */
+string firstName = "John";
+string lastName = "Doe";
+string name = $"My full name is: {firstName} {lastName}";
+Console.WriteLine(name);

W3School-CSExercises/CS-Strings/csStringsE4.cs

@@ -0,0 +1,12 @@
+/**
+ *	from C# Strings: Exercise 4 ( https://www.w3schools.com/cs/exercise.asp?filename=exercise_strings4 )
+ *
+ *	question:
+ *	Access the first character (H) in myString and print the result:
+ *
+ *	string myString = "Hello";
+ *	Console.WriteLine(___________);
+ *
+ */
+string myString = "Hello";
+Console.WriteLine(myString[0]);

W3School-CSExercises/CS-Strings/csStringsE5.cs

@@ -0,0 +1,12 @@
+/**
+ *	from C# Strings: Exercise 5 ( https://www.w3schools.com/cs/exercise.asp?filename=exercise_strings5 )
+ *
+ *	question:
+ *	Use the correct property to print the length of the txt string.
+ *
+ *	string txt = "Hello";
+ *	Console.WriteLine(___.______);
+ *
+ */
+string txt = "Hello";
+Console.WriteLine(txt.Length);

W3School-CSExercises/CS-Strings/csStringsE6.cs

@@ -0,0 +1,12 @@
+/**
+ *	from C# Strings: Exercise 6 ( https://www.w3schools.com/cs/exercise.asp?filename=exercise_strings6 )
+ *
+ *	question:
+ *	Use the correct method to output the value of the txt string to upper case letters.
+ *
+ *	string txt = "Hello World";
+ *	Console.WriteLine(txt._________);
+ *
+ */
+string txt = "Hello World";
+Console.WriteLine(txt.ToUpper());