output?

[Ankur kothari]

  int []arr = {1,2,3,4};
for ( int i : arr )
{
	System.out.println(i);
   arr[i] = 0;
}   

why does this print me
1
0
3
0

[W. Joe Smith]

Using this loop, the first time through you pull the first array element and assign it to i, therefore i = 1. It will print 1, then assign array element arr[1] = 0. Going through the 2nd time, you set i = 0, since that is now the 2nd element in the array. Then you set arr[0] = 0. Then you pull the 3rd element, 3, and assign it to i. Then you set arr[3] = 0. Then you pull the 4th element, 0, and print it. Then you set arr[0] = 0, and the loop finishes.

The important thing to remember here is arrays are zero-based.

[Ankur kothari]

Thanks Joe.......How you doin?

[Minhaj Mehmood]

Ankur kothari wrote:

  int []arr = {1,2,3,4};
for ( int i : arr )
{
	System.out.println(i);
   arr[i] = 0;
}   

why does this print me
1
0
3
0

The iteration is:

loop will run the length of arr;(i.e. 4)
arr{0=1, 1=2, 2=3, 3=4}

first iteration whereas: i=arr[0]=1;
System.out.println(i); // i=1;
arr[i]=0; //arr[1]=0

second iteration whereas: i=arr[1]=0; as we altered arr[1] position in first iteration;
System.out.println(i); // i=0;
arr[i]=0; //arr[0]=0

third iteration whereas: i=arr[2]=3;
System.out.println(i); // i=3;
arr[i]=0; //arr[3]=0


fourth iteration whereas: i=arr[3]=0; as we alter arr[3]=0 position in third iteration;
System.out.println(i); // i=0;
arr[3]=0; //arr[3]=0

Loop exits;

Hope its clear to you now.


Minhaj

[Ankur kothari]

[Ankit Garg]

Ankur, when you post a mock exam question, please QuoteYourSources of the question.

Also please UseAMeaningfulSubjectLine for your topics. Instead of writing "output?" if you write something like "confusion in enhanced for loop output", it makes more sense...