GATE CSE 2024 | Set 1 | Question: 27

Question

​Consider the following syntax-directed definition $\text{(SDD)}$.

$$\begin{array}{|l|l|} \hline  \text{$S \rightarrow D H T U$} & \text{$ \left\{S.v a l = D.val + H.val + T.val + U.val;\right\}$} \\ \hline D \rightarrow ^{"} \mathrm{M}^{"} D_1 & \left\{D.val =5+D_{1}.val; \right\} \\ \hline D \rightarrow \epsilon & \left\{D.val = -5; \right\} \\ \hline H \rightarrow ^{"}\mathrm{L}^{"} H_1 & \left\{H.val = 5^{*} 10+H_{1}.v a l;\right\} \\ \hline
H \rightarrow \epsilon &  \left\{H.val = -10; \right\} \\ \hline
T \rightarrow \text {"C" } T_1 & \left\{T.v a l=5^{*} 100+T_{1}. val;\right\} \\ \hline                                            T \rightarrow \epsilon & \left\{T . v a l= - 5;\right\} \\ \hline                                                                                U \rightarrow \text{"K"} & \left\{U . v a l=  5;\right\} \\ \hline \end{array}$$

Given $\text{"MMLK"}$ as the input, which one of the following options is the $\text{CORRECT}$ value computed by the $\text{SDD}$ (in the attribute $S.val$)?

• A. $45$
• B. $50$
• C. $55$
• D. $65$ 

Comments

All questions related to Syntax Directed Definitions(SDD):

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Compiler Design: GATE CSE 2024 | Set 1 | Question: 27

Compiler Design: GATE CSE 2024 | Set 2 | Question: 19

Compiler Design: GATE CSE 2025 | Set 2 | Question: 12

Answer 1

Answer :  45

Comments

Why there no Derivation from T-> CT1->T->e ???

Please answer ..

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@Ayush 3 cuz we don't need "C" in string "MMLK"

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If someone is confused like I was about quotes (" ")
actually the alphabets inside quotes are terminals. quotes are just used to show them like that here.

So we first generated the parse tree then inputed the values according to the rules.

Also, in  D->"M"D1 .... D1 is just another instance of D.

Answer 2

So the output of the given SDT is $45$.

Option $(A)$ is correct.

Similar types of concepts asked in  GATE CSE 2023 | Question: 50

Answer 3

So, the output of the given SDT is 45.

Answer 4

ansewer is 45