Eroare de compilare: user.cpp:23:2: warning: no newline at end of file user.cpp: In function 'long int compare(const void*, const void*)': user.cpp:7: error: no match for 'operator-' in '*(per*)b - *(per*)a' user.cpp: In function 'int main()': user.cpp:12: error: 'stdin' was not declared in this scope user.cpp:12: error: 'freopen' was not declared in this scope user.cpp:13: error: 'stdout' was not declared in this scope user.cpp:15: error: 'q' was not declared in this scope user.cpp:15: error: 'w' was not declared in this scope user.cpp:15: error: 'n' was not declared in this scope user.cpp:15: error: 'scanf' was not declared in this scope user.cpp:17: error: 'i' was not declared in this scope