ch1_solutions.md

Ch1 Exercise Solutions

1. The below methods can be applied:

   scala> 3                 
   !=   /    >>>            doubleValue   hashCode        isValidByte    min          synchronized     toHexString     unary_-      
   ##   <    ^              ensuring      intValue        isValidChar    ne           to               toInt           unary_~      
   %    <<   abs            eq            isInfinite      isValidInt     notify       toBinaryString   toLong          underlying   
   &    <=   asInstanceOf   equals        isInfinity      isValidLong    notifyAll    toByte           toOctalString   until        
   *    ==   byteValue      floatValue    isInstanceOf    isValidShort   round        toChar           toRadians       wait         
   +    >    ceil           floor         isNaN           isWhole        self         toDegrees        toShort         |            
   -    >=   compare        formatted     isNegInfinity   longValue      shortValue   toDouble         toString        →            
   ->   >>   compareTo      getClass      isPosInfinity   max            signum       toFloat          unary_+                      

2. Result differs from 3 by 4.440892098500626E-16.

   scala> import scala.math._
   import scala.math._
   
   scala> sqrt(3)
   res0: Double = 1.7320508075688772
   
   scala> pow(res0, 2)
   res1: Double = 2.9999999999999996
   
   scala> 3 - res1
   res2: Double = 4.440892098500626E-16

3. res variables are val.

   scala> var myVar = 2
   myVar: Int = 2
   
   scala> val myVal = 2
   myVal: Int = 2
   
   scala> 2
   res0: Int = 2
   
   scala> myVar += 1
   
   scala> myVar
   res2: Int = 3
   
   scala> myVal += 1
   <console>:13: error: value += is not a member of Int
     Expression does not convert to assignment because receiver is not assignable.
          myVal += 1
                ^
   
   scala> res0 += 1
   <console>:13: error: value += is not a member of Int
     Expression does not convert to assignment because receiver is not assignable.
          res0 += 1
               ^

4. Per http://scala-lang.org/api/current/scala/collection/immutable/StringOps.html#*(n:Int):String, this operation returns the current string concatenated n times.

   scala> "crazy" * 3
   res0: String = crazycrazycrazy

5. Per http://scala-lang.org/api/current/scala/Int.html#max(that:Int):Int, the max method returns the larger of this and that.

   scala> 10 max 2
   res0: Int = 10

6. scala> val x: BigInt = 2
   x: BigInt = 2
   
   scala> x.pow(1024)
   res0: scala.math.BigInt = 179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216

7. scala> import math.BigInt
   import math.BigInt
   
   scala> import BigInt.probablePrime
   import BigInt.probablePrime
   
   scala> import util.Random
   import util.Random
   
   scala> probablePrime(100, Random)
   res0: scala.math.BigInt = 1153228787909717743149305360789

8. scala> math.BigInt.probablePrime(100, util.Random).toString(36)
   res0: String = 2naon5my2lpsnqrc11xj

9. scala> val myStr = "abcd"
   myStr: String = abcd
   
   scala> myStr(0)
   res0: Char = a
   
   scala> myStr.last
   res1: Char = d
   
   scala> 

10. See http://scala-lang.org/api/current/scala/collection/immutable/StringOps.html for descriptions of take, drop, takeRight, and dropRight. The advantage over substring is that they take a single index argument instead of two. Also, they are arguably more intuitive to use.