Compilare: user.cpp: In function ‘int main()’: user.cpp:39:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < sir.length()) ^ user.cpp:53:76: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[j] >= '0' && sir[j] <= '9' && j < sir.length()) ^ user.cpp:64:72: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[j] >= '0' && sir[j] <= '9' && j < sir.length()) ^