Programming Language Concepts and Compilation
Definition of Algorithm
The following definition: “Prescription for a set of logical steps to solve the same type” corresponds to:
| A | Boolean Logic | C | An algorithm |
| B | A programming language | D | A computer program |
Answer: (C)
Stored Program Concept
When the sequence of instructions to be executed by a computer is stored in main memory, it is said that the computer is programmed internally, and this defines:
| A | Source language | C | Stored program |
| B | Target language | D | Program Instructions |
Answer: (C)
Batch and Integral Processing
Batch Processing
These are processes where the inputs and outputs are data files in batches, whose records are processed by consignment by a program.
Integral Processing
These are processes where the computer system and computers are an integral part of a larger system, and a computer failure usually means higher system failure as well.
Syntax Definition
The arrangement of words as elements in a sentence to show a specific relationship, described by the sequence of symbols that can build effective programs, is the definition of:
| A | Semantics | C | Syntax |
| B | A programming language | D | A computer program |
Answer: (C)
Elements of Language Syntax
In general, the syntax of a language style is set by the choice of several basic elements of syntax. Three of the seven most prominent watched in class are:
| A | Character Set, symbols of operation, optional words | C | Character Set, white, meanings |
| B | Keys and reserved words, data dictionary, comments | D | None of the above |
Answer: (A)
Common Functions of a Semantic Analyzer
The exact functions of the semantic analyzer vary substantially, depending on the language and logical organization of the translator. Two of the most common are:
| A | Operation characters Handling optional words | C | Maintenance of the symbol table Error Detection |
| B | Register of reserved words Interruptions of data | D | None of the above |
Answer: (C)
Lexical Analysis
It is the start of any translation to group the sequence of characters into its elemental parts: identifiers, delimiters, operation symbols, numbers, keywords, optional, white, comments, and everything else. The results are the same lexical items or tokens.
Optimization in Program Translation
Optimization as a stage in program translation refines the result of the semantic analyzer, evaluating the versatility and efficiency produced by this and producing, in most cases, an object program with better performance.
Syntactic Unit
A sequence of lexemes forms a syntactic unit such as an expression, a sentence, a statement, or a call to a subprogram.
Machine Language
The program stored in computer memory so it can run is written in:
| A | A source language | C | An algorithm |
| B | A programming language | D | A machine language |
Answer: (D)
Compiler Front End
It is part of a compiler that analyzes the source code, checks its validity to a tree branch, and fills in the values of the symbol table. It is often independent of the platform which will compile.
| A | Front End | C | Stored program |
| B | Object Code | D | Back End |
Answer: (A)
Language Interpreter
A language interpreter analyzes the source program and runs it directly without generating any equivalent code. Its action is equivalent to that of a human interpreter, who translates phrases heard on the fly without producing any permanent writing. Examples of interpreters are the languages BASIC, Lisp, and Prolog.
Mainframe Computers
Large computers meet a range of users either for batch processes or to address several linked workstations.
Ambiguity in Language Design
A central problem in the design of any language is when it supports two or more different interpretations in executing an operation or set of instructions:
| A | Lack of definition | C | Semantic error |
| B | Syntax Error | D | Ambiguity |
Answer: (D)
Syntactic Elements of Language
Expressions and statements are identified as:
| A | Programs and sub-structures | C | Operation symbols |
| B | Syntactic elements of language | D | Basic instructions of a language |
Answer: (B)
Syntactic Analysis and Link/Load Process
Syntactic Analysis
Here, the structural elements of the program (statements, declarations, expressions, etc.) are identified using the lexemes produced by the lexical analyzer.
Link and Load
This stage, when the program refers to external data or other applets, links and loads the various segments of the translated code in memory, using a table attached to link properly addresses the data and programs at the code where necessary.
Terminal Symbols
The symbols used to form chains, derived from grammar rules of a language, are called terminal symbols. After the translation of the program has been optimized, it must be assembled in declarations and statements that can be read in machine language, which is the output of the translation.
Code Generation
This stage in program translation is known as:
| A | Construction and sub-program | C | Code Generation |
| B | Semantic Analysis | D | Language production |
Answer: (C)
Basic Differences Between Programming Languages
All programs specify a set of operations applied to certain data in a certain sequence. There are basic differences between the languages in three basic aspects:
A) Type of data that support, type of operations available, and mechanisms to control the sequence of operations
B) Types that support reading, memory types available, and mechanisms to control the sequence of operations
C) Type of sequence data that support, type of codes available, and mechanisms to monitor operations
D) Type of mechanism to control data, type of transactions available, and sequence of operations
Answer: (A)
Elementary Data Objects
A data object is elementary if:
| A | Is an aggregate of other data objects | C | Contains a data value that is always manipulated as a unit |
| B | Is an array of other data objects | D | Contains a data value that is always manipulated as an object |
Answer: (C)
Data Type, Stored Representation, and Abstract Data Type
Data Type
A data type is a kind of integrated data object to a set of operations to create and manipulate.
Stored Representation
The stored representation represents data objects of the data types in computer memory during program execution.
Abstract Data Type
An abstract data type is defined as:
- A set of data objects, using one or more definitions of types
- A set of abstract operations on these data objects
- Encapsulation of the sets so that the user of the new type cannot manipulate the data objects except for using defined operations.
Abstraction Support in Programming Languages
A programming language provides support for abstraction in two ways:
A) 1 provided space for two objects by providing aid to the programmer to design process tools
B) A virtual computer 2 provided a facilitator helps the programmer to build abstractions
C) One providing a virtual link two data providing aid to the programmer to establish redundancy
D) Providing a support structure for facilitating the programmer abstractions in February to build virtual links
Answer: (B)
Largest Block of Storage
The largest block of storage on any system should be designated to store:
| A | Control routines memory manager at runtime | C | The code segments that represent user-compiled programs |
| B | Keys and keywords, data dictionary, comments | D | None of the above |
Answer: (C)
Information Concealment
Information concealment is primarily a matter of program design. An abstraction is encapsulated effectively only when the language prohibits access to information hidden in the abstraction.
Storage Elements
Elements that require storage:
- Segments of code for compiled programs
- Programs runtime system
- Data structures and user-defined constants
- Return subprogram points
- Temporary evaluation of expressions
Sequence Control Structure Categories
Sequence control structures can be categorized into four groups. Two of them are:
- Expressions
- Declarations
- Declarative programming
- Subprograms
Syntax Tree
Parsing imposes a hierarchical structure to the chain of lexical components performed using syntactic trees.
Compiler Phases: Front End and Back End
In 1958, Strong and others proposed a solution where a compiler could be used by several machines. This is done by dividing the compiler into two phases:
| A | Analyzer and Synthesizer | C | Front End and Back End |
| B | Translator and Integrator | D | None of the above |
Answer: (C)
Compiler Error Detection
The phases that usually handle a large proportion of errors detected by the compiler are:
| A | Lexical Analyzer | C | Code Optimization |
| B | Syntactic and Semantic Analysis | D | Code Generation |
Answer: (B)
Compiler vs. Interpreter
Compilers translate during development time before the program runs. The compiler receives the source code, analyzes, optimizes, and translates it into machine language, creating a complete program ready for implementation.
Interpreters translate during runtime. As the program runs, the interpreter translates instructions into machine language.
Software Tools for Source Code Analysis
Many software tools manipulate source programs by performing some analysis first. Examples include:
- Structure Editors: Analyze program text and give it a hierarchical structure.
- Pretty Printers: Analyze and print a program to make its structure clear.
- Static Checkers: Analyze a program to discover potential errors without running it.
- Interpreters: Perform the operations of the source program instead of producing an object program.
Module Design in Large Programs
Large programs are divided into components called modules. Module design usually includes two aspects:
- Functional decomposition of the program
- Data decomposition of the program
Memory Allocation Demand
The operation often requiring the most memory allocation is the activation of a subprogram record and other information upon calling a subprogram.
Static Memory Management
The simplest form of allocation is static mapping. Storage segments of program code and system users are assigned statically, such as I/O buffers and various miscellaneous system data.
Infix Notation
Infix notation is suitable for binary operations, where the operation symbol is written between the two operands, commonly used for arithmetic, relational, and logical operations.
Information Hiding
Information hiding is primarily a program design concern. Abstraction is effectively encapsulated only when the language prevents access to the hidden information within the abstraction.
Abstraction Support and Storage Allocation
A programming language supports abstraction in two ways:
- Providing a virtual computer
- Providing tools for programmers to build abstractions
The largest storage block should be designated for user-compiled program code segments.
Temporary Storage Areas
Input and output operations usually work through buffers, temporary storage areas holding data between transfer and program processing.
Compiler vs. Assembler
Compilers translate higher-level source code into machine code during development, while assemblers translate assembly language (a low-level language) into machine code. Assembly language has a near one-to-one correspondence with machine instructions.
Lexicographic Recognition
In the late 1950s, Rabin and Scott proposed using deterministic and nondeterministic automata for lexicographic recognition (the process of identifying and categorizing words or tokens in a sequence of characters).