Compilare: user.cpp: In function ‘int main()’: user.cpp:91:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ~^~~~~~~~~~ user.cpp: In function ‘int expresie()’: user.cpp:52:12: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized] return val; ^~~