Why doesn't this work for checking a win?

sorry if im getting annoying but this is due tomorrow at midnight and i have no idea what im doingCode:`//Check xWin`

bool xwin(string l1,string l2,string l3)

{

if (l1=="xxx")

return true;

if (l3=="xxx")

return true;

if (l2=="xxx")

return true;

if (l1[1]=="x" && l2[1]=="x" && l3[1]=="x")

return true;

if (l1[0]=="x" && l2[1]=="x" && l3[2]=="x")

return true;

if (l1[0]=="x" && l2[0]=="x" && l3[0]=="x")

return true;

if (l1[2]=="x" && l2[1]=="x" && l3[0]=="x")

return true;

if (l1[2]=="x" && l2[2]=="x" && l3[2]=="x")

return true;

else

return false;

}