打印以下图案（用循环实现）。 * *** ***** ******* ***** *** *

是Java代码实现：

for (int i = 1; i <= 4; i++) {
    for (int j = 1; j <= 2 * i - 1; j++) {
        System.out.print("*");
    }
    System.out.println();
}
for (int i = 3; i >= 1; i--) {
    for (int j = 1; j <= 2 * i - 1; j++) {
        System.out.print("*");
    }
    System.out.println();
}

输出结果为：

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

以下是C++代码实现：

#include <iostream>
using namespace std;

int main() {
    int num;
    while (cin >> num) {
        for (int i = 1; i <= num; i++) {
            for (int j = 1; j <= num - i; j++) {
                cout << " ";
            }
            for (int k = 1; k <= 2 * i - 1; k++) {
                cout << "*";
            }
            cout << endl;
        }
        for (int i = num - 1; i >= 1; i--) {
            for (int j = 1; j <= num - i; j++) {
                cout << " ";
            }
            for (int k = 1; k <= 2 * i - 1; k++) {
                cout << "*";
            }
            cout << endl;
        }
    }
    return 0;
}

输出结果为：

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