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up vote 6 down vote favorite

Having read SO, just found this question:

if (x > y)
     print (x)
else if (x < y)
     print (y)
else
     print (x,y)

How many branches and decisions are there? It mentiones there should be 3 decision and 5 branches, yet I cannot see how. For me I can only imagine 4 branches (2 Ifs with two possible results).

Original question here

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3 Answers

up vote 3 down vote 
           if
          /  \    < ---- 2 branches
      false true
      else 
       if
      /  \        < ---- 2 branches
   false true
   else 
    |             < ---- 5th and final branch

as else part gives a decision, it is a branch too

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That is why I do not understand either. There is no decision in the else part, it just a result of FALSE in the previous ELSE IF. – user970696 Jan 31 at 8:55
1  
@user970696 See, when a true or false condition of an IF is met you do some operation in it, in the same way you do an operation even when an ELSE part is reached. As that ELSE part has some functionality, it is taken as a branch. – Vivekanand S V Jan 31 at 9:02
Exactly but when the ELSE IF evaluates to FALSE, no operation can be done and the flow continues with ELSE. What can you do between ELSE IF>FALSE and ELSE? – user970696 Jan 31 at 9:05
1  
If the test-is-false condition and the else part count as separate branches for the second if, then why not for the first, making it a total of 6 branches? – Bart van Ingen Schenau Jan 31 at 9:18
@BartvanIngenSchenau You have 2 decision outcomes for both IFs..but it would make 4. The last ELSE just continues from the False branch of the second IF. That is why I think 4 is enough. – user970696 Jan 31 at 9:23
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up vote 0 down vote

I think it depends a bit on how you would define decision and branch. From a logical perspective I would say that there are 3 branches, because of the 3 calls to print. Since two ifs are used, there are two decisions made.

On a machine level this might look different, because the compiler will generate code that might involve more branches and decisions. For example the compiler could generate code for the test x==y.

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up vote 0 down vote accepted

Investigating this a bit more, I concluded that the statement about this code having 5 branches is incorrect. This code definitely has only 4 branches - 4 edges to traverse. As IF has always two branches (one for true and one for false), with two IFs there are 4 branches in the code. The diagram of this case (IF, ELSE IF, ELSE) is as follows. You can easily see only four branches:

enter image description here

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