Sure, here's a simple C++ program that will print a triangle of stars:

```
#include <iostream>

int main() {
    int rows;
    std::cout << "Enter number of rows: ";
    std::cin >> rows;
    for (int i = 1; i <= rows; i++) {
        for (int j = 1; j <= i; j++) {
            std::cout << "* ";
        }
        std::cout << std::endl;
    }
    return 0;
}
```

This program prompts the user for the number of rows to print, and then uses two nested loops to print the correct number of stars on each line. The outer loop iterates over each row, and the inner loop iterates over each star on that row. The program outputs a space after each star so that the triangle looks neat and tidy.
Genera un programma C++ per stampare un triangolo di stelle.