Array Set in scala

Question

I have code in scala :

 val graph = new Array [Set[Int]] (n)

 def addedge(i:Int,j:Int)
 {
     graph(i)+=j
 }

What does graph(i)+=j mean? Can anybody translate it in any other languages like c, c++ or java?

dhg · Accepted Answer · 2012-08-19 18:49:54Z

7

graph is an Array, just like in C or Java. graph(i) means "access the ith element of graph". Each element in graph is a Set of Ints. The += method on Set adds an item to the Set. So graph(i) += j adds the number j into the Set stored at index i in graph.

Trying things out in the REPL shows the behavior:

scala> val graph = Array(Set(1,2), Set(2,3), Set(1))
graph: Array[scala.collection.immutable.Set[Int]] = Array(Set(1, 2), Set(2, 3), Set(1))

scala> graph(1) += 4

scala> graph
res0: Array[scala.collection.immutable.Set[Int]] = Array(Set(1, 2), Set(2, 3, 4), Set(1))

edited Aug 19, 2012 at 18:49

answered Aug 19, 2012 at 18:41

dhg

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2 Comments

user194611 Over a year ago

how about this one ?'for(i<-0 until n) { graph(i)=Set[Int](); }'

dhg Over a year ago

@user194611, ask a new question as a new question

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