Compilare: main.cpp: In function 'std::string secv2()': main.cpp:35:11: warning: statement has no effect [-Wunused-value] 35 | for ( i; i >= 0; i-- ) | ^ main.cpp: In function 'std::string secv3()': main.cpp:47:11: warning: statement has no effect [-Wunused-value] 47 | for ( i; i >= 0; i-- ) | ^