Language: C++

#include<iostream>
#include<string>
#include<cstdio>
using namespace std;
char n[12][12];
char figure[7][4][4] = {
	{"1100","1100","0000","0000"},
	{"1000","1000","1000","1000"},
	{"1111","0000","0000","0000"},
	{"0100","1100","1000","0000"},
	{"1100","0110","0000","0000"},
	{"1000","1100","0100","0000"},
	{"0110","1100","0000","0000"}
};

int main(){
	for(int i=0; i<12; i++)
		for(int j=0; j<12; j++)
			n[i][j]='0';
	
	while(~scanf("%8s\n%8s\n%8s\n%8s\n%8s\n%8s\n%8s\n%8s\n\n", n[0], n[1], n[2], n[3], n[4], n[5], n[6], n[7])){
		for(int i=0; i<8; i++)
			for(int j=0; j<8; j++)
				cin >> n[i][j];

		for(int i=0; i<7; i++){
			for(int j=0; j<8; j++){
				for(int k=0; k<8; k++){
					bool flag=true;
					
					for(int x=0; x<4; x++){
						for(int y=0; y<4; y++){
							if(figure[i][x][y] != n[j+x][k+y]) flag = false;
						}
					}
					
					if(flag){
						cout << (char)('A'+i) << endl;
					}

				}
			}
		}
	}
	return 0;
}

Compiler output:
a.cc:7:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
    7 |         {"1100","1100","0000","0000"},
      |          ^~~~~~
a.cc:7:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
    7 |         {"1100","1100","0000","0000"},
      |                 ^~~~~~
a.cc:7:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
    7 |         {"1100","1100","0000","0000"},
      |                        ^~~~~~
a.cc:7:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
    7 |         {"1100","1100","0000","0000"},
      |                               ^~~~~~
a.cc:8:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
    8 |         {"1000","1000","1000","1000"},
      |          ^~~~~~
a.cc:8:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
    8 |         {"1000","1000","1000","1000"},
      |                 ^~~~~~
a.cc:8:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
    8 |         {"1000","1000","1000","1000"},
      |                        ^~~~~~
a.cc:8:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
    8 |         {"1000","1000","1000","1000"},
      |                               ^~~~~~
a.cc:9:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
    9 |         {"1111","0000","0000","0000"},
      |          ^~~~~~
a.cc:9:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
    9 |         {"1111","0000","0000","0000"},
      |                 ^~~~~~
a.cc:9:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
    9 |         {"1111","0000","0000","0000"},
      |                        ^~~~~~
a.cc:9:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
    9 |         {"1111","0000","0000","0000"},
      |                               ^~~~~~
a.cc:10:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
   10 |         {"0100","1100","1000","0000"},
      |          ^~~~~~
a.cc:10:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
   10 |         {"0100","1100","1000","0000"},
      |                 ^~~~~~
a.cc:10:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
   10 |         {"0100","1100","1000","0000"},
      |                        ^~~~~~
a.cc:10:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
   10 |         {"0100","1100","1000","0000"},
      |                               ^~~~~~
a.cc:11:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
   11 |         {"1100","0110","0000","0000"},
      |          ^~~~~~
a.cc:11:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
   11 |         {"1100","0110","0000","0000"},
      |                 ^~~~~~
a.cc:11:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
   11 |         {"1100","0110","0000","0000"},
      |                        ^~~~~~
a.cc:11:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
   11 |         {"1100","0110","0000","0000"},
      |                               ^~~~~~
a.cc:12:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
   12 |         {"1000","1100","0100","0000"},
      |          ^~~~~~
a.cc:12:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
   12 |         {"1000","1100","0100","0000"},
      |                 ^~~~~~
a.cc:12:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
   12 |         {"1000","1100","0100","0000"},
      |                        ^~~~~~
a.cc:12:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
   12 |         {"1000","1100","0100","0000"},
      |                               ^~~~~~
a.cc:13:10: error: initializer-string for 'char [4]' is too long [-fpermissive]
   13 |         {"0110","1100","0000","0000"}
      |          ^~~~~~
a.cc:13:17: error: initializer-string for 'char [4]' is too long [-fpermissive]
   13 |         {"0110","1100","0000","0000"}
      |                 ^~~~~~
a.cc:13:24: error: initializer-string for 'char [4]' is too long [-fpermissive]
   13 |         {"0110","1100","0000","0000"}
      |                        ^~~~~~
a.cc:13:31: error: initializer-string for 'char [4]' is too long [-fpermissive]
   13 |         {"0110","1100","0000","0000"}
      |                               ^~~~~~