解:?$(1)$?原式?$=(-3)^2-2^2-\{2×[(-3)^3-1]-\frac {1}{2}\}÷ (-3-2)$?
?$=9-4-[2×(-27-1)-\frac {1}{2}]×(-\frac {1}{5})$?
?$=5-(-\frac {113}{2})×(-\frac {1}{5})=5-\frac {113}{10}=-\frac {63}{10}$?
?$(2)$?由于程序中有分?jǐn)?shù),而分母不能為?$0$?,即當(dāng)?$b=0$?時(shí)程序無(wú)法操作
程序中含有?$(a-b)$?的項(xiàng),且為除數(shù),而除數(shù)不能為?$0$?,即當(dāng)?$b=a$?時(shí)程序無(wú)法操作
∴有兩種可能:輸入?$b=0$?或?$a=b$?