Java Programming - Flow Control - Discussion

Discussion Forum : Flow Control - Finding the output (Q.No. 15)
15.
What will be the output of the program?
public class Delta 
{ 
    static boolean foo(char c) 
    {
        System.out.print(c); 
        return true; 
    } 
    public static void main( String[] argv ) 
    {
        int i = 0; 
        for (foo('A'); foo('B') && (i < 2); foo('C')) 
        {
            i++; 
            foo('D'); 
        } 
    } 
}
ABDCBDCB
ABCDABCD
Compilation fails.
An exception is thrown at runtime.
Answer: Option
Explanation:

'A' is only printed once at the very start as it is in the initialisation section of the for loop. The loop will only initialise that once.

'B' is printed as it is part of the test carried out in order to run the loop.

'D' is printed as it is in the loop.

'C' is printed as it is in the increment section of the loop and will 'increment' only at the end of each loop. Here ends the first loop. Again 'B' is printed as part of the loop test.

'D' is printed as it is in the loop.

'C' is printed as it 'increments' at the end of each loop.

Again 'B' is printed as part of the loop test. At this point the test fails because the other part of the test (i < 2) is no longer true. i has been increased in value by 1 for each loop with the line: i++;

This results in a printout of ABDCBDCB

Discussion:
15 comments Page 1 of 2.

Dilipkumarsah said:   1 decade ago
When foo ("A") is executed in the intilizing section of loop then the funtion return a boolean value. But there is no any varible to catch it. So this program thorw an error in runtime.

Dinesh said:   1 decade ago
Hi guys, this program will not execute "i<2" since there is a short circuit operator, right? So this program will not terminate and produce an error at runtime. Guys if anyone know pls clarify me?

Sahil said:   1 decade ago
Try to run this code, it will neither produce any output nor throws exception...

Rajendra said:   1 decade ago
@Sahil.

Did you really tried to run this program?

It gave me output as mentioned in option A.

Yatin sharma said:   1 decade ago
The code using short circuit operator for the check i.e. && due to which the right hand condition will not be checked and loop will be infinite.

Madhu said:   1 decade ago
The code is perfect and produces the output as mentioned in option A.

Gaurav said:   1 decade ago
How can D print after B.

And again after D it print C.

Can any one explain this process?

Riya said:   1 decade ago
Right @Gaurav My Question is same as yours.

How come D prints before B, and then C is also being printed? Any one please answer this?

Brajesh said:   1 decade ago
Three loop are going to run.

1. Will print ABDC.

2. BDC.

3. CB.

Friends you will see that there are there section of for loop.

Shankar said:   10 years ago
I also fail to understand the result, can anyone please explain the for loop in detail and the output with regards to it?


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