Questions and Answers of Concepts of Programming Languages

Compute the weakest precondition for each of the following sequences of assignment statements and their postconditions:a. a = 2 * b + 1; b = a - 3 {b < 0}b. a = 3 * (2 *
What is the problem with using a software pure interpreter for operational semantics?
Compute the weakest precondition for each of the following selection constructs and their postconditions:a. if (a == b) b = 2 * a + 1 else b = 2 *
Explain what the preconditions and postconditions of a given statement mean in axiomatic semantics.
Explain the four criteria for proving the correctness of a logical pretest loop construct of the form while B do S end.
Describe the approach of using axiomatic semantics to prove the correctness of a given program.
Prove that (n + 1) * c* n = 1.
Describe the basic concept of denotational semantics.
Prove the following program is correct:{n > 0}count = n;sum = 0;while count <> 0 do sum = sum + count; count = count - 1;end{sum = 1 + 2 + . . . + n}
What are three reasons why syntax analyzers are based on grammars?
Design a state diagram to recognize one form of the comments of the C- based programming languages, those that begin with /* and end with */.
Explain the three reasons why lexical analysis is separated from syntax analysis.
Perform the pairwise disjointness test for the following grammar rules.a. S → aSb І bAAb. A → b{aB} І ac. B → aB І a
Design a state diagram to recognize the floating- point literals of your favorite programming language.
Define lexeme and token.
What three extensions are common to most EBNFs?
Using the grammar in Example 3.2, show a parse tree and a leftmost derivation for each of the following statements:A = A * (B + (C * A))Data From Example 3.2: → → A| BIC → + | * |( ) |
Define a left-recursive grammar rule.
Write a BNF description of the Boolean expressions of Java, including the three operators &&, ||, and ! and the relational expressions.
What is the difference between a sentence and a sentential form?
Rewrite the BNF of Example 3.4 to add the ++ and -- unary operators of Java.Data from Example 3.4: → → A | B|C → + | → * | → ( ) |
Describe the operation of a general language recognizer.
Rewrite the BNF of Example 3.4 to give + precedence over * and force + to be right associative.Data From Example 3.4: → → A | B|C → + | → * | → ( ) |
Describe the operation of a general language generator.
Write EBNF descriptions for the following:a. A Java class definition header statementb. A C switch statement
Who are language descriptions for?
The two mathematical models of language description are generation and recognition. Describe how each can define the syntax of a programming language.
Define syntax and semantics.
To what is a JSP document converted by a JSP processor?
What element of the JSTL is related to a subprogram?
What is the output of an XSLT processor?
What are the inputs to an XSLT processor?
What is the primary platform on which C# is used?
What deficiency of the switch statement of C is addressed with the changes made by C# to that statement?
Is Lua normally compiled, purely interpreted, or impurely interpreted?
What data structures are built into Lua?
What characteristic of Ruby’s arithmetic operators makes them unique among those of other languages?
What characteristic does Ruby share with Smalltalk?
What data structure does Python use in place of arrays?
PHP’s primary data structure is a combination of what two data structures from other languages?
What is the relationship between JavaScript and PHP, in terms of their use?
For what application area is JavaScript most widely used?
What two languages was the original version of Perl meant to replace?
What array structure is included in C# but not in C, C++, or Java?
How does the typing system of PHP and JavaScript differ from that of Java?
What characteristic of Java is most evident in JavaScript?
What was the first application for Java?
What is the primary application for Objective-C?
From what language does Objective-C borrow its syntax for method calls?
Why does C++ include the features of C that are known to be unsafe?
What three concepts are the basis for object-oriented programming?
What populates the Smalltalk world?
What Ada construct provides support for abstract data types?
What are the concurrent program units of Ada called?
What is the primary application area for which Ada was designed?
What are the two kinds of statements that populate a Prolog database?
What are two characteristics of C that make it less safe than Pascal?
What operators in C were modeled on similar operators in ALGOL 68?
What language introduced the case statement?
What design criterion was used extensively in ALGOL 68?
What innovation of data structuring was introduced in ALGOL 68 but is often credited to Pascal?
What features of SIMULA 67 are now important parts of some object-oriented languages?
For what new line of computers was PL/I designed?
PL/I was designed to replace what two languages?
Why was Basic an important language in the early 1980s?
What user group was the target of the first version of Basic?
What organization was most responsible for the early success of COBOL (in terms of extent of use)?
Give a brief general description of a markup-programming hybrid language.
What data structure that appeared in COBOL originated with Plankalkül? What organization was most responsible for the early success of COBOL (in terms of extent of use)?
Why, in your opinion, do new scripting languages appear more frequently than new compiled languages?
In what year did the COBOL design process begin?
Explain two reasons why pure interpretation is an acceptable implementation method for several recent scripting languages.
On what programming language was COBOL based?
In recent years data structures have evolved within scripting languages to replace traditional arrays. Explain the chronological sequence of these developments.
What language was designed to describe the syntax of ALGOL 60?
There have been some public interchanges between Microsoft and Sun concerning the design of Microsoft’s J++ and C# and Sun’s Java. Read some of these documents, which are available on their
What missing language element of ALGOL 60 damaged its chances for widespread use?
Build a table identifying all of the major language developments, together with when they occurred, in what language they first appeared, and the identities of the developers.
In what version of ALGOL did block structure appear?
Languages continually evolve. What sort of restrictions do you think are appropriate for changes in programming languages? Compare your answers with the evolution of Fortran.
What two professional organizations together designed ALGOL 60?
Do you think language design by committee is a good idea? Support your opinion.
What dialect of Lisp is used for introductory programming courses at some universities?
What is your opinion of the argument that languages that are too complex are too dangerous to use, and we should therefore keep all languages small and simple?
In what way are Scheme and Common Lisp opposites of each other?
Are there any logic programming languages other than Prolog?
Where was Lisp developed? By whom?
What are the arguments both for and against the idea of a type less language?
Why were linguists interested in artificial intelligence in the late 1950s?
What is the primary reason why PL/I became more widely used than ALGOL 68?
Which version of Fortran was the first to have character string handling?
Describe, in your own words, the concept of orthogonality in programming language design.
Which version of Fortran was the first to have any sort of dynamic variables?
Was IBM’s assumption, on which it based its decision to develop PL/I, correct, given the history of computers and language developments since 1964?
What control flow statements were added to Fortran IV to get Fortran 77?
Outline the major motivation of IBM in developing PL/I.
What was the most significant feature added to Fortran I to get Fortran II?
Why, in your opinion, did COBOL allow long identifiers when Fortran and ALGOL did not?
What was the source of all of the control flow statements of Fortran I?
Describe in detail the three most important reasons, in your opinion, why ALGOL 60 did not become a very widely used language.

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