Compilare: user.cpp: In function ‘int main()’: user.cpp:43:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( size_t i = 0 ; i < n; i++ ) ^ user.cpp:52:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( size_t i = 0; i < m; i++ ) ^ user.cpp:61:12: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if ( j == 0 ) ^