Assignment 3 Programming Language Concepts

Name : Alvin Theodora
NIM   : 1801428434

Here is the third assignment of Programming Language Concepts course. The question is taken from "Concepts of Programming Language, 10th edition" from Robert W. Sebesta in chapter 3:

Review Questions

1.       Define syntax and semantics.

= Syntax and semantics are related to each other, and both terms are used in relation to aspects of language. Syntax is the form of its language expressions, statements, and program units. Semantics is the meaning of those expressions and statements.

2.       Who are language descriptions for?

= Language description is like an instruction to use the language itself. Hence, the language description is made for the implementers, user, and also software developer to determine the semantics of a programming language.

3.       Describe the operation of a general language generator.

= A general language generator is a device that can be used to generate the sentences of a language. However, it generates sentence that is unpredictable, therefore a language generator is a limited usefulness as a language descriptor

4.       Describe the operation of a general language recognizer.

= A language recognizer is used to indicate whether the input of a given string is in a specific language or not. A language recognizer is capable of reading characters or string in the language. Such devices are like filters to determine whether the syntax is from a specific language.

5.       What is the difference between a sentence and a sentential form?

= A sentence of a language is generated through sequence of the grammar’s rules. And, sentential form is each of the strings in the derivation of a grammar in programming language

Problem Set

1.       The two mathematical models of language description are generation and recognition. Describe how each can define the syntax of a programming language.

= A language recognizer is capable of reading characters or string in the language and determines whether the programs are in the specific language and syntactically correct. And a language generator is used to define the syntax of a language is true or not.

2.       Write EBNF descriptions for the following:

a.       A java class definition header statement

b.      A Java method call statement

c.       A C switch statement

d.      A C union definition

e.      C float literals

 a. a java class definition header statement

= <class_head> ® {<modifier>} class <id> [extends class_name] [implements<interface_name> {, <interface_name>}] <modifier> ® public | abstract | final<class_head> ® {<modifier>} class <id> [extendsclass_name] [implements<interface_name> {, <interface_name>}] <modifier> ® public | abstract | final

b. a Java method call statement

= <for> -> for ‘(‘ [[<type>] <id> = <expr> {, [<type>] <id> = <expr>}] ; [<expr>] ; [<expr>{, <expr>}] ‘)’ ‘{‘ <stmt_list> ‘}’

 c. a C switch statement

= <stmt>    ->   switch ( <int expr> ) {

case <int const> :  { <stmt> ; }

{ case <int const> :  { <stmt> ; }}

[ default :  { <stmt>  ;  } ]

}

d. a C union definition

= <union_defn> -> union <var_list> <union_identifier>;

<var_list> -> <list_of_data-type specifier> <var>

<list_of_data-type specifier> -> int | float | long |char | double

<union_identifier> -> <var>

e.      C float literals

= <float-literal> –>   <real> <suffix>

| <real> <exponent> <suffix>

| <integer> <exponent> <suffix>

3.       Rewrite the BNF of Example 3.4 to give + precedence over * and force + to be right associative.

= <assign>→<id>=<expr>
<id>→A|B|C
<expr>→< term >*< expr >| <term>
<term>→<term>+<factor>| <factor>
<factor>→(<expr>) | <id>



4.      Rewrite the BNF of Example 3.4 to add the ++ and – unary operators of Java.

= <assign> -> <id> = <expr>

<id> -> A | B | C

<expr> -> <expr> + <term> | <term>

<term> -> <term> * <factor> | <factor>

<factor> -> ( <expr> ) | <id> | <id> ++ | <id> - -

5.       Write a BNF description of the Boolean expressions of Java, including the three operators &&, ||,         and ! and the relational expressions.

= <Boolean_expr> -> <Boolean_expression> || <Boolean_term> | <Boolean_term>

<Boolean_term> -> <Boolean_term> && <Boolean_factor> | <Boolean_factor>

<Boolean_factor> -> id | ! <Boolean_factor> | ( <Boolean_expr> ) | <relation_expr>

<relation_expr> -> id = = id | id != id | id < id | id <= id | id >= id | id > id