For Loop Logic Iteration Why not behaving Same ?

Question

I have tried to Increasing Number By one Like this

for (int i = 0; i < 10; i++) {
            System.out.println("Count " + i);

        }

this logic Works fine.

but when i try to make it As user input for the series its not giving same out put from 0

See this

Scanner scanner = new Scanner(System.in);
        // System.out.println(scanner.hasNextInt());
        if (scanner.hasNextInt()) {
            // System.out.println(scanner.nextInt());
            System.out.println(Integer.parseInt(scanner.next()));
            for (int i = 0; i < Integer.parseInt(scanner.next()); i++) {
                System.out.println("Count " + i);
            }
        }

its not giving out put by increasing element its giving if i input for example 12 Out Put:-

15
Count 0

Can any body can say why?

Besides the calling `next()` twice, without knowing your input, it might be: http://stackoverflow.com/questions/13102045/skipping-nextline-after-use-next-nextint-or-other-nextfoo-methods — Mark Rotteveel, May 05 '15 at 13:56
for (int i = 0; i < Integer.parseInt(scanner.next()); i++) { System.out.println("Count " + i); } using single next also giving same input — Kishan Bheemajiyani, May 05 '15 at 14:01

score 2 · Accepted Answer · answered May 05 '15 at 13:56

2

You're calling scanner.next() twice. The first time all you do is print it out, and then discard it.

Try putting it in a variable instead:

//this could use scanner.nextInt() instead
int limit = Integer.parseInt(scanner.next()); 
System.out.println(limit);
for (int i = 0; i < limit; i++) {
    //...

answered May 05 '15 at 13:56

Mark Peters

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1

Actually the OP is potentially calling `scanner.next()` *lots* of times - once before the loop, and then once *per iteration* of the loop. – Jon Skeet May 05 '15 at 13:59
okey just trying using single this one for (int i = 0; i < Integer.parseInt(scanner.next()); i++) { System.out.println("Count " + i); } still same result. – Kishan Bheemajiyani May 05 '15 at 14:02
@JonSkeet i think little i got it it will take number of numbers into the input isnt it if will give 15 it will take it as 1 right 0,1 isnt it ? – Kishan Bheemajiyani May 05 '15 at 14:05
@Krishna: I didn't follow that comment *at all* but I suggest you review how a `for` loop works - the whole condition is evaluated on each iteration, so when the condition includes `Integer.parseInt(scanner.next())` it will try to read another token on each iteration... – Jon Skeet May 05 '15 at 14:23
@JonSkeet okey jon so i got it it will try to find every time new input isnt it? so its giving 0 in out put. – Kishan Bheemajiyani May 05 '15 at 14:35

score 1 · Answer 2 · answered May 05 '15 at 13:56

1

Each call to scanner.next() reads a new token, which you parse to int.

You have to store the first input and reuse it :

    Scanner scanner = new Scanner(System.in);
    // System.out.println(scanner.hasNextInt());
    if (scanner.hasNextInt()) {
        int len = Integer.parseInt(scanner.next());
        System.out.println(len);
        for (int i = 0; i < len; i++) {
            System.out.println("Count " + i);
        }
    }

answered May 05 '15 at 13:56

Eran

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Same thing i have done in this Integer.parseInt(scanner.next()); why its not working then. – Kishan Bheemajiyani May 05 '15 at 13:59

For Loop Logic Iteration Why not behaving Same ?

2 Answers2