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// Lecture 1
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25
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//===========
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14
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// Assignments (values)
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// (variable names should be lower case)
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//======================================
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val x = 42
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val y = 3 + 4
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// Collections
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//=============
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List(1,2,3,1)
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Set(1,2,3,1)
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1 to 10
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(1 to 10).toList
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(1 until 10).toList
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// an element in a list
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List(1, 2, 3, 1)(0)
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List(1, 2, 3, 1)(3)
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1::2::3::Nil
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List(1, 2, 3) ::: List(4, 5, 6)
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// Printing/Strings
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//==================
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println("test")
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val tst = "This is a " + "test"
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println(tst)
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val lst = List(1,2,3,1)
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println(lst.toString)
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println(lst.mkString("\n"))
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// some methods take more than one argument
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println(lst.mkString("[", ",", "]"))
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// Conversion methods
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//====================
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List(1,2,3,1).toString
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List(1,2,3,1).toSet
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"hello".toList
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1.toDouble
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List(1,2,3,4).reverse
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// Types
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//=======
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/* Scala is a strongly typed language
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* Base types
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Int, Long, BigInt, Float, Double
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String, Char
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Boolean
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* Compound types
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List[Int],
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Set[Double]
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Pairs: (Int, String)
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List[(BigInt, String)]
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*/
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// Smart Strings
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//===============
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println(">\n<")
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println(""">\n<""")
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/* in Java
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val lyrics = "Baa, Baa, Black Sheep \n" +
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"Have you any wool? \n" +
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"Yes, sir, yes sir \n" +
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"Three bags full"
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*/
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val lyrics = """Baa, Baa, Black Sheep
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|Have you any wool?
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|Yes, sir, yes sir
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|Three bags full""".stripMargin
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println(lyrics)
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// Pairs/Tuples
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//==============
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val p = (1, "one")
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p._1
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p._2
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val t = (4,1,2,3)
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t._4
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// Hello World
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//=============
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// show an example of a stand-alone scala file
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// remind that in the course work you are asked a
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// plain scala "work-sheet"
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// Function Definitions
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//======================
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def square(x: Int): Int = x * x
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square(6)
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// If control structure
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//======================
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def fact(n: Int): Int =
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if (n == 0) 1 else n * fact(n - 1)
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/* boolean operators
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== equals
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! not
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&& || and, or
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*/
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def fact2(n: BigInt): BigInt =
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if (n == 0) 1 else n * fact2(n - 1)
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fact2(150)
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def fib(n: Int): Int =
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if (n == 0) 1 else
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if (n == 1) 1 else fib(n - 1) + f(n - 2)
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//a recursive function
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def gcd(x: Int, y: Int): Int = 2 //???
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25
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// String Interpolations
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//=======================
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14
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// Assert/Testing
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//================
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// For-Maps (not For-Loops)
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//==========================
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14
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for (n <- (1 to 10).toList) yield square(n)
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for (n <- (1 to 10).toList;
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m <- (1 to 10).toList) yield m * n
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val mtable = for (n <- (1 to 10).toList;
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m <- (1 to 10).toList) yield m * n
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mtable.sliding(10,10).mkString("\n")
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// Webpages
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//==========
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