prog.cpp: In function ‘int main()’:
prog.cpp:9:27: error: request for member ‘length’ in ‘n’, which is of non-class type ‘long long unsigned int’
for (int i = 0; i < n.length(); i++)
^~~~~~
prog.cpp:11:16: error: invalid types ‘long long unsigned int[int]’ for array subscript
if (n[i] == 4 || n[i] == 7)
^
prog.cpp:11:29: error: invalid types ‘long long unsigned int[int]’ for array subscript
if (n[i] == 4 || n[i] == 7)
^
prog.cpp:16:11: error: ‘i’ was not declared in this scope
if (n[i] == 4 || n[i] == 7)
^