Compilare: user.cpp: In function ‘int main()’: user.cpp:38:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < sir.length()) ^ user.cpp:50:76: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[j] >= '0' && sir[j] <= '9' && j < sir.length()) ^ user.cpp:60:72: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(sir[j] >= '0' && sir[j] <= '9' && j < sir.length()) ^