Trying to understand nested iteration statements

[Aasokeo]

I've been working along in C# quite nicely, but I can't wrap my head around the idea of nested iteration statements. I understand that it's pretty much a loop in a loop, but I can't trace the code of a nested iteration statement and tell you what the output will be. Nor can I do the reverse - writing code to generate a certain output.

Here are the three exercises I'm having trouble understanding:

[QUOTE]1. Write a program that generates the following output:

*
**
***
****
*****
******
*******
********

2. Write a program that generates the following output:

*
########
**
#######
***
######
****
#####
*****
####
******
###
*******
##
********
#

3. What is the output from the following nested pair of for loops (Trace the source code.)[/QUOTE]

for(int i = 1; i < 4; i++)
{
      for(int j = 1; j < 5;  j++)
     {
          Console.Write("  {0}", i+j);
     }
}

What's the best way to tackle this? How can I better understand this concept?
(I've peeked at the answers, but I haven't got any idea WHY they are the answers. I will post them if requested.)

Any explanation is appreciated :buddy:

[esalaka]

For example that example of yours writes 1+1, 1+2, 1+3, 1+4, 1+5, then starts a new round of the top-level loop, again reseting j to 1.

If that's what you were after.

[Aasokeo]

Okay I'm getting a clearer picture...the outer loop represents the number of lines (3 in this case) and the inner represents what will be printed on each of the lines. j increases for each iteration until it reaches 4 (hence four results per line), then we start from the outer loop again...

So the second line is 2+1, 2+2, 2+3, 2+4. And the third 3+1, 3+2 and so on...

So the output would be
2 3 4 5
3 4 5 6
4 5 6 7
And the answer key confirms my guess :buddy: Okay I've got that much clear, thanks esa.

Now for the first two.... :sigh:
Well for the first one, there are eight lines. So I'm gonna guess the first line looks like:

for(int i = 1; i < 9; i ++)

And as for the inner loop, I haven't the slightest idea :frown:

[ZeekyHBomb]

The inner loop must be 'dynamic'. Hint: use i in the inner loop declaration.

[esalaka]

Even more of a hint: You need to print as many characters as the value of i is. What could you do to print one character for each one in i if you consider i a summmation of the form i = 1 + 1 + … + 1

Spoiler contains a fairly direct answer, don't read unless you've tried it lots of times.
[sp]You would iterate from 1 to i[/sp]