Java for loop question

ScissorPaperRock

How does one initialise an int in a for loop if the value is unknown. Say for instance it would be entered through keyboard input.

Sherifu

If you take it in before the for loop, you wouldn't initialise it. You'd just leave that part of the for loop blank.

Creamy Goodness

for(int i = 0 ; i < valueReadFromKb ; i++){
...
//do stuff here
...
}

ScissorPaperRock

Creamy Goodness wrote: »

for(int i = 0 ; i < valueReadFromKb ; i++){
...
//do stuff here
...
}

Yeah I could create another int and initialise that one, and update that one.
But what I was wondering was if I could convert the outside while loop of this to a for loop - where numOfStars is entered through keyboard

int numOfStars = scanner.nextInt();
int countMax = numOfStars;
int row = numOfStars;

while(numOfStars>0)
{
for(row = numOfStars; row<=countMax; row++)
{
System.out.print("*");
}
System.out.println(" ");
numOfStars--;
row=numOfStars;
}



If I leave that part of the loop blank it doesn't work, unless Im doing something wrong

Thanks for the help!

Sherifu

I was talking about something like;

for(; numOfStars<=countMax; numOfStars++)

but I see you want to use numOfStars outside the for loop.

ScissorPaperRock

Sherifu wrote: »

If you take it in before the for loop, you wouldn't initialise it. You'd just leave that part of the for loop blank.

Ah that worked - i didn't realise I had to put in the ; to leave it blank

Cheers!

ScissorPaperRock

Sherifu wrote: »

I was talking about something like;

for(; numOfStars<=countMax; numOfStars++)

but I see you want to use numOfStars outside the for loop.

Yeah I'm using it outside the for loop but it's been initialised outside the loop beforehand so it seems ok to leave it blank in the for loop. It works anyway!

ScissorPaperRock

Can anyone explain why it doesn't work the same when I take the "row = numOfStars" out of the second for loop, even though I've previously initialised it as such.

Thanks again

blackgold>>

ever hear of a debugger?:rolleyes:

ScissorPaperRock

blackgold>> wrote: »

ever hear of a debugger?:rolleyes:

Yep! But this whole programming thing is new to me and I wouldn't be too sure how to use one. I thought they showed errors, whereas this isn't an error per se, it's a matter of the code working in a manner other than I intended when I format it differently.

But from thinking about it a bit more I've realised that it's behaving differently when I convert it to a for loop because the sequence has changed. i.e.

if I had taken the row = numOfStars out of the for loop while the numOfStars-- was moved to a for loop (rather than at the end of a while loop) then the numOfStars decrement is happening after the row=numOfStars which is not what I needed.

You learn something new everyday!

blackgold>>

try programing without a language its easier:)
maybe your spending to much time on java and not enough planning your solution.

ScissorPaperRock

blackgold>> wrote: »

try programing without a language its easier:)
maybe your spending to much time on java and not enough planning your solution.

My solution?

I just completed a module on Java, and quite enjoyed it. So I was just experimenting a little.

Maybe you spend too much time judging and not enough time saying something useful

blackgold>>