Language: C++

#include<iostream>
using namespace std;

int main() {
	int H, W;
	for (;;) {
		cin >> H >> W;
		if (H == 0 && W == 0)break;
		for (int i = 0; i < H; i++) {
			for (int j = 0; j < W; j++) {
				cout << "#";
			}
			cout << endl;
		}
??????????????????cout<<endl;

	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:1: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      | ^
a.cc:15:2: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |  ^
a.cc:15:3: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |   ^
a.cc:15:4: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |    ^
a.cc:15:5: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |     ^
a.cc:15:6: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |      ^
a.cc:15:7: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |       ^
a.cc:15:8: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |        ^
a.cc:15:9: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |         ^
a.cc:15:10: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |          ^
a.cc:15:11: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |           ^
a.cc:15:12: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |            ^
a.cc:15:13: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |             ^
a.cc:15:14: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |              ^
a.cc:15:15: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |               ^
a.cc:15:16: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |                ^
a.cc:15:17: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |                 ^
a.cc:15:18: error: expected primary-expression before '?' token
   15 | ??????????????????cout<<endl;
      |                  ^
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token
a.cc:15:29: error: expected ':' before ';' token
   15 | ??????????????????cout<<endl;
      |                             ^
      |                             :
a.cc:15:29: error: expected primary-expression before ';' token