Compilare: user.cpp: In function ‘int main()’: user.cpp:20:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0 ; i < strlen( sir ) ; i ++ ){ ^ user.cpp:23:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( j = i + 1 ; j < strlen( sir ) && ok ; j ++ ){ ^ user.cpp:48:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1 ; i < strlen( sir ) - 1 ; i ++ ){ ^ user.cpp:59:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0 ; i < strlen( sir ) ; i ++ ) g << sir[ i ]; ^