parambirs · August 14, 2019 23:11 · Dec 23, 2014 · Apr 2, 2014
diff --git a/s4di_ch01_exercises.sc b/s4di_ch01_exercises.sc
@@ -20,10 +20,12 @@ object chap01 {
 // 4. Scala lets you multiply a string with a number - try out "crazy" * 3 in the REPL.
 // What does this operation do? Where can you find it in Scaladoc?
   "crazy" * 3                                     //> res0: String = crazycrazycrazy
-
+// Can be found in the StringOps class
+
 // 5. What does 10 max 2 mean? In which class is the max method defined?
   10 max 2                                  //> res1: Int = 10
-
+// Defined in the RichInt class
+
 // 6. Using BigInt, compute 2^1024.
   BigInt(2) pow 1024                        //> res2: scala.math.BigInt = 17976931348623159077293051907890247336179769789423
                                                   //| 0657273430081157732675805500963132708477322407536021120113879871393357658789

diff --git a/s4di_ch01_exercises.sc b/s4di_ch01_exercises.sc
@@ -0,0 +1,63 @@
+package src.exercises
+
+import scala.math._
+import BigInt.probablePrime
+import util.Random
+
+object chap01 {
+// 1. In the Scala REPL, type 3. followed by the Tab key. What methods can be
+// applied?
+// => Do it in REPL. There are many methods including %, &, *, +, toByte, toChar etc.
+
+// 2. In the Scala REPL, compute the square root of 3, and then square that value.
+// By how much does the result differ from 3? (Hint: The res variables are your
+// friend.)
+  println(3 - pow(sqrt(3), 2))                    //> 4.440892098500626E-16
+
+// 3. Are the res variables val or var?
+// val
+
+// 4. Scala lets you multiply a string with a number - try out "crazy" * 3 in the REPL.
+// What does this operation do? Where can you find it in Scaladoc?
+  "crazy" * 3                                     //> res0: String = crazycrazycrazy
+
+// 5. What does 10 max 2 mean? In which class is the max method defined?
+  10 max 2                                  //> res1: Int = 10
+
+// 6. Using BigInt, compute 2^1024.
+  BigInt(2) pow 1024                        //> res2: scala.math.BigInt = 17976931348623159077293051907890247336179769789423
+                                                  //| 0657273430081157732675805500963132708477322407536021120113879871393357658789
+                                                  //| 7688144166224928474306394741243777678934248654852763022196012460941194530829
+                                                  //| 5208500576883815068234246288147391311054082723716335051068458629823994724593
+                                                  //| 8479716304835356329624224137216
+
+// 7. What do you need to import so that you can get a random prime as
+// probablePrime(100, Random), without any qualifiers before probablePrime and Random?
+  // import BigInt.probablePrime
+  // import util.Random
+  probablePrime(100, Random)                //> res3: scala.math.BigInt = 912013777957722342425952556723
+
+// 8. One way to create random file or directory names is to produce a random
+// BigInt and convert it to base 36, yielding a string such as "qsnvbevtomcj38o06kul".
+// Poke around Scaladoc to find a way of doing this in Scala.
+  probablePrime(100, Random).toString(36)   //> res4: String = 2w2bxtp6lz08l502sg9h
+
+// 9. How do you get the first character of a string in Scala? The last character?
+  val s = "String"                          //> s  : String = String
+  s.head                                    //> res5: Char = S
+  s(0)                                      //> res6: Char = S
+  s.last                                    //> res7: Char = g
+  s(s.length - 1)                           //> res8: Char = g
+
+// 10. What do the take, drop, takeRight, and dropRight string functions do? What
+// advantage or disadvantage do they have over using substring?
+  // take: Selects the first n elements
+  s.take(2)                                 //> res9: String = St
+  // drop: Selects all elements except first n ones
+  s.drop(2)                                 //> res10: String = ring
+  // takeRight: Selects the last n elements
+  s.takeRight(2)                            //> res11: String = ng
+  // dropRight: Selects all elements except last n ones
+  s.dropRight(2)                            //> res12: String = Stri
+  // advantage: they are much more concise and intuitive than substring
+}