Thread: a slightly different triangle

I've looked through many old posts and have not seen one like this. I know creating a triangular shape composed of *'s is common, but this one's a little different.
This is how the output should look:

1
12
123
1234
123
12
1

I have tried to write some code, but I substituted *'s for numbers to see if I could get that to work first. As usual, it's not working. Could anyone give me some idea where I'm going wrong. Thanks.

Code:

 #include <iostream>
using namespace std;

//Functions prototypes...
void instructions ();	
int triangle ();

//----------------------------------

int main ()
{
                instructions ();
	triangle ();

return 0;
}

//--------------------------------------------------------------------------

// User instructions 
void instructions ()
{
	cout << "This program displays the numbers 1 through 4 "
		 << "in incremental steps, " << endl;
	cout << "starting with just 1 on the first line " 
	     << "and increasing each line by one digit " << endl;
	cout << "until the fourth line has all 4 numbers.  " 
	     << "It then starts displaying the numbers" << endl;
	cout << "in decremental steps until the final line "
		 << "just displays the number 1." << endl << endl;
}	// End of instructions function

//-----------------------------------------------------------------

int triangle ()
{
		//Local variables:
	int horiz=0;
	int vert=0;


	for(int vert=1; vert<=4; vert++)
	{
		for(int horiz=1; horiz<=3; horiz++)
		cout << "*";
		{
			for(int horiz=1;horiz<=vert; horiz++)
				cout << "*";
		}
	cout << endl;
	}
	return 0;
}