Draw parse tree for this :

Ans:

Here's the BNF notation for the grammar of the minimal programming language:

::$=\{"$;$"\}$

::$=$

$|$

$|$

$|$

$|$

::$=$ "read"

::$=$ "write" $(|)$

::$="="$

::$="$if$"$ "then" $\{"$;$"\}$ "else" $\{"$;$"\}$ "end"

::$=$ "while" $"$do$"\{"$;$"\}$ "end"

::$=\{("+"|"-")\}$

::$=\{("*"|"/")\}$

::$=$

$|$

$|"("")"$

::$=("="|"<"|">")$

::$=$ letter $\{$ letter $\}$

::$=$ digit $\{$ digit $\}$

::$=\text{'}"\text{'}\{$ letter $\}\text{'}"\text{'}$

Example Program

Below is a sample program in the language defined by the above grammar. This program reads an integer and displays "Even" if the value is even, and "Odd" if the value is odd.

read x;

if x $-($x $/2)*2=0$ then

write "Even"

else

write "Odd"

end