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8 章 习题

8 章 习题. 1. 设有表达式 A*(B*C-A)≤B+C∧D a. 试写出逆波兰式中间代码。 b. 试写出三元式中间代码。 c. 试写出树中间代码。 d. 试写出四元式中间代码。. 解： a.ABC*A-*BC+≤D∧ 两种形式. b. ①(*, B, C) ②(-,①, A) ③(*, A,②) ④(+, B, C) ⑤(≤,③,④) ⑥(∧,⑤,D). 6. c. ∧. 5. ≤. D. +. 3. 4. *. C. B. -. A. 2. *. A. 1. C. B.

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8 章 习题

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  1. 8章 习题 1.设有表达式A*(B*C-A)≤B+C∧D a.试写出逆波兰式中间代码。 b.试写出三元式中间代码。 c.试写出树中间代码。 d.试写出四元式中间代码。 解：a.ABC*A-*BC+≤D∧ 两种形式

  2. b. ①(*, B, C) ②(-,①, A) ③(*, A,②) ④(+, B, C) ⑤(≤,③,④) ⑥(∧,⑤,D)

  3. 6 c. ∧ 5 ≤ D + 3 4 * C B - A 2 * A 1 C B

  4. d. 1.(*, B, C, T1) 2.(-, T1, A, T2) 3.(*, A, T2, T3) 4.(+, B, C, T4) 5.(≤,T3, T4, T5) 6.(∧, D, T5, T6)

  5. 2.试写出下列语句的四元式中间代码. a.IF x>0 THEN x:=0 ELSE x:=1 b.WHILE x>0 DO x:=x-1 c.IF x>0 THEN x:=x-1 ELSE IF x<0 THEN x:=x+1 ELSE x:=1 d.WHILE x>0 DO WHILE y>0 DO BEGIN y:=y-x;x:=x-1 END

  6. 解：a. 1. (>, x , 0 , T1) 2. (then, T1, ——, ——) 3. (:=, 0, ——, x ) 4. (else, ——, ——, ——) 5. (:=, 1, ——, x ) 6. (ifend, ——, ——,——)

  7. b. 1.(while,——,——,——) 2.( >, x , 0 ,T1) 3.(do , T1,——,——) 4.(——, x, 1,T2) 5.(:=, T2,——,x) 6.(whend,——,——,——)

  8. c. 1.(>, x , 0 , T1) 2.(then, T1, —, —) 3.(—, x , 1 , T2) 4.(:=, T2, —, x ) 5.(else, —, —, —) 6.(<, x , 0 , T3) 7.(then, T3, —, —) 8.(+, x , 1 , T4) 9.(:=, T4, —, x )

  9. 10.( else, —, —, —) 11.( := , 1 , —, x ) 12.(ifend, —, —, —) 13.(ifend, —, —, —)

  10. d. 1.(while, —, —, —) 2.( > , x , 0 ,T1) 3.( do , T1, —, —) 4.(while, —, —, —) 5.( > , y , 0 ,T2) 6.( do , T2, —, —) 7.( — , y ,x , T3) 8.( := , T3,—, y ) 9.( — , x , 1 ,T4)

  11. 10.( := , T4, —,x ) 11.(whend, —, —, —) 12.(whend, —, —, —)

  12. 3.试写出下列赋值语句的四元式中间代码： a.A[i+1]:=A[i-1]+A[i] b. R.f:=R.x+a[i] c.B[i].x:=R1.D[j].y d. A[A[i]]:=R2.R.f e.D[i+1][j]:=D[i+1][j]+1 其中各数组的各界类型为1..10

  13. 1.( +, i, 1, T1) • 2.(—, T1, 1, T2) • 3.( *, T2, L, T3) • 4.([], A, T3, T4) (A[i+1]) • 5.( -, i, 1, T5) • 6.(—, T5, 1, T6) • 7.( *, T6, L, T7) (A[i-1]) • 8.([], A, T7, T8) • 9.(—, i, 1, T9) • 10.( *, T9, 5, T10)

  14. 11.([], A, T10, T11) (A[i]) 12.( +, T7, T11, T12) 13.(:=, T12, —, T13)

  15. b. 1.(. , R, offf, T1) (R.f) 2.(. , R, offx, T2) (R.x) 3.(- , i, 1, T3) 4.( *, T3, 5, T4) 5.([], A, T4, T5) (A[i]) 6.( +, T2, T5, T6) 7.(:=, T6, —, T7)

  16. c.1.(-, i, 1, T1) 2.(*, T1, l, T2) B[i] 3.([ ], B, T2, T3) 4.(., T3, offx, T4) 5.(., R1, offD[j].y, T5) 6.( -, j, 1, T6) 7.(*, T6, l, T7) D[j] 8.([ ], D, T7, T8) 9.(., T8, offy, T9) 10.(:=, T9, _, T4)

  17. d.1.(-, i, 1, T1) 2.(*, T1, l, T2) 3.([ ], A, T2, T3) 4.(-, T3, 1, T4) 5.(*, T4, l, T5) 6.([ ], A, T5, T6) 7.(。, R2, offR.f, T7) 8.(。， R, offf, T8) 9.(:=, T8, -, T6)

  18. e.1.(+, i, 1, T1) 2.(-, T1, 1, T2) 3.(*, T2, l, T3) 4.([ ], D, T3, T4) 5.(-, j, 1, T5) 6.(*, T5, l, T6) 7.([ ], T4, T6, T7) 8.(+, T7, 1, T8) 9.(:=, T8, -, T7)

  19. 4.试写出下列过程语句的四元式中间代码： a.f(X*(X+1),i+1) b.f(g(X-1), X) c.f(g(h(X),g(X)) 其中f,g,h的形参均为赋值形参变量。

  20. 解:a. 1.( +, x, 1, T1) 2.( *, x, T1, T2) 3.( +, i, 1, T3) 4.( act, T2, 1, 4) 5.( act, T3, 1, 5) 6.(call, f, —,—)

  21. b. 1.( - , x, 1, T1) 2.(act, T1, 1, 4 ) g(x-1) 3.(call, g, _, T2) 4.(act, T2, 1, 4 ) 5.(act, x, 1, 5 ) 6.(call, f, _, _ )

  22. c.1.(act, x, 1, 4 ) 2.(call, h, _,T1) h(x) 3.(act, T1, 1, 4 ) 4.(call, g, _, T2) g(h(x)) 5.(act, x, 1, 4 ) 6.(call, g, _, T3) g(x) 7.(act, T2, 1, 4 ) 8.(act, T3, 1, 5 ) 9.(call, f, _, _ )

  23. 5.设有表达式 A-(A*B-D*(A-B*D))/A 写出生成三元式的过程。 解: ⑴ (*， A, B) ⑵ (*, B, D) ⑶ (-, A, ⑵) ⑷ (*, D, ⑶) ⑸ (-, ⑴, ⑷) ⑹ (1, ⑸, A) ⑺ (-, A, ⑹)

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