nested For loops

Hey everyone,
I feel like I've asked this question before, and I searched through all my posts and couldnt find it, so I may just be going crazy, and if not I apologize for the redundancy.

So, I'm trying to use nested for loops to created a pyramid of X's,
as in:
......X
....XXX
..XXXXX
XXXXXXX etc...the dots are there to be abe to format the triangle, I don't need them in the program...

and I have the following code, but I have absolutely no idea how to insert the X's and I was looking for a push in the right direction NOT THE ACTUAL CODE...thanks a lot! :( <Helpless Chap

Code:

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//Chapter 3
//Exercise 5

#include <iostream>
using namespace std;

int main()
{
        const char X = 'X';
        const char SPACE = '.';
        unsigned int i;

        for (i = 0; i < 21; i++)
        {
                for (int spaces = 0; spaces < 21; spaces++)
                {
                        cout << SPACE;
                        if (spaces == 10)
                        {
                                cout << X;
                                //I want to use a for loop to print X to screen
                        }
                }
                cout << endl;
        }
        return 0;
}

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Assume that you're using a monospace font.

The nth row has (2n-1) Xs, by observation.
The nth row also has N-n preceding spaces, where N is the number of Xs in the last row.

Effectively,

Code:

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Given n rows to be printed
for i=1 to i=n
        for j=1 to j=n-i
                print space
        for k=1 to k=2i-1
                print X

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