Compilare: user.cpp: In function ‘int main()’: user.cpp:83:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ~^~~~~~~~~~ user.cpp: In function ‘int expresie()’: user.cpp:20:9: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized] int val; ^~~