格林模拟试题二(下)(6)

 
question 48)
given the following variables
char c = 'c';int i = 10;double d = 10;long l = 1;string s = "hello";
which of the following will compile without error?
1)c=c+i;
2)s+=i;
3)i+=s;
4)c+=s;

question 49)
1) file f = new file("/","autoexec.bat");
3) outputstreamwriter o = new outputstreamwriter(system.out);

question 50)
interface iface{}class cface implements iface{}class base{}public class obref extends base{   public static void main(string argv){    obref ob = new obref();    base b = new base();    object o1 = new object();    iface o2 = new cface();   }}
2)b=ob;
4)o1=b;
given the following code what will be the output?
1) 10030
3) 209930