Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Joseph P. Mohr 1. 2. 3. 4. 5. C# Overview Scheme Overview T-SQL Overview Language Comparisons Conclusions Object-Oriented Language Type-Safe Evolved from C Main application is server-side scripting in the .NET Framework Developed in 2001 Current version is 4.0 C# is designed for component-oriented programming Software Components ◦ Increasingly used in modern software design ◦ Self-contained and self-describing ◦ Have their own documentation Versioning ◦ Allows the language to evolve without breaking programs in older versions. ◦ Supports virtual and override modifiers. ◦ Method overloading that supports versioning. ◦ Explicit interface member declarations. Virtual and Override ◦ If a method is declared virtual, then the implementation evokes is determined at run-time. ◦ Non-Virtual methods have the implementation determined at compile-time. ◦ The override modifier can be used to provide another implementation for an existing virtual method. C# programs are comprised of the following: ◦ ◦ ◦ ◦ ◦ Programs Namespaces Types Members Assemblies Consist of one or more source files Source files contain the other structural elements of the program Declared at the top of the source file with the using directive Avoid having to use the fully qualified names in the source code. Most common types: ◦ Classes ◦ Interfaces Can contain members and namespaces Either reference or value With reference type, two variables can affect the same object. Most common members: ◦ ◦ ◦ ◦ Fields Methods Properties Events Made up of Intermediate Language (IL) and metadata Use Just-In-Time (JIT) compiling Implement applications or libraries and have the .exe or .dll file extension respectively Using System; Class Hello { Static void Main() { Console.Out.WriteLine(“Hello, World”); } } C# uses two different grammars, the Lexical grammar and the syntactic grammar. Lexical grammar defines line terminators, white space, comments, tokens, and preprocessing directives. Syntactic grammar defines how the tokens from the lexical grammar are combined into programs. Compiled language results in fast execution. High performance is a result of being derived from the C family. Boxing and Unboxing operations are the most common detriments to performance. ◦ Can be avoided by declaring as Object Pros: ◦ Clearly defined data types ◦ Familiar, well designed syntax Cons: ◦ Feature multiplicity ◦ Operator Overloading Pros: ◦ Excellent support for abstraction ◦ Strong expressivity with control sections Cons: ◦ Large number of different contstructs Classes derived from the base Object Class, which includes implementation of the primitives, can be simply combined to create very robust and diverse data structures. Type-Checking: ◦ C# is considered a type-safe language and the compiler can catch type errors in almost all cases. ◦ There are pointers supported by the language which can prevent the compiler from catching typeerrors. Exception Handling: ◦ Highly functional and similar to Java Aliasing: ◦ Reference types can be referring to the same memory location and is considered a detriment to reliability. The modular design considerations of C# makes the code highly portable. Self-contained documentation in all the modules makes for easier portability amongst different software developers. MS Visual C# MS Visual Studio using using using using using using System; System.Collections.Generic; System.Linq; System.Web; System.Web.UI; System.Web.UI.WebControls; namespace WebApplication2 { public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void Calendar1_DayRender(object sender, DayRenderEventArgs e) { EventDataContext edc = new EventDataContext(); var query = from ev in edc.Events where ev.Date == e.Day.Date select ev; e.Cell.VerticalAlign = VerticalAlign.Top; e.Cell.BorderColor = System.Drawing.Color.Teal; e.Cell.BorderWidth = 1; e.Cell.BorderStyle = BorderStyle.Solid; } } } foreach (var ev in query) { HyperLink link = new HyperLink(); link.ForeColor = System.Drawing.Color.Teal; link.NavigateUrl = "~/EventInfo.aspx?event=" + ev.EventNo; link.Text = ev.Name; Button but = new Button(); e.Cell.Controls.Add(new LiteralControl("<p>")); e.Cell.Controls.Add(link); e.Cell.Controls.Add(new LiteralControl("</p>")); } www.myjaxcalendar.com Functional programming language Evolved from LISP Created in 1975 at MIT by Guy L. Steele and Gerald J. Sussman Originally called Schemer to mimic the naming convention used by other languages evolved from LISP, such as Conniver Considerably more minimalist than Common Lisp, but supports tools for language extension. Most commonly used for lambda calculus and as an educational tool by introductory level computer science classes. Lambda calculus is a logical system of computation through the use of binding and substitution. Scheme programs are interpreted. Program Elements: Keywords Variables Structured forms Constant data (numbers, characters, strings, quoted vectors, quoted lists, quoted symbols, etc.) ◦ Whitespace ◦ Comments ◦ ◦ ◦ ◦ Program expressions are known as sexpressions S-expressions are made up of structured forms and lists. S-expressions are delineated by matching sets of opening and closing parentheses. List-processing primitives: ◦ car – the first element in a list ◦ cdr – all the other elements in the list ◦ cons – constructs lists First-class functions (functions can be assigned to variables) Only the inner-most binding of a variable is visible in an expression. Inner bindings are said to “shadow” the outer bindings. This type of scoping is known as “lexical scoping”. Expression: ◦ (cdr (car ‘((1 2 3) 4 5))) Result: ◦ (2 3) Scheme executes faster and more efficiently than Common LISP as a result of its minimalist design. Pros: ◦ Overall Simplicity of the language, including a lack of feature multiplicity, improves the readability of the language. ◦ Identifiers are not restricted in length. Cons: ◦ The dynamic variable types which aren’t explicitly declared to be of a certain data type. Pros: ◦ The overall simplicity of the language, especially over that of Common LISP Cons: ◦ Weak support for abstraction ◦ Lacking expressivity Simply supports the most commonly used data structures including Strings and Enums. Lacking in the ability to combine primitives in to complex data structures. Pros: ◦ Lack of aliasing ◦ Performs run-time type checking Cons: ◦ Does not have a good system for exception handling. Scheme programs are highly portable between the same version of Scheme. The very high number of versions of Scheme in use is major stumbling block to the portability of Scheme. Some of the many flavors of scheme are: ◦ SISC – runs off of the JVM ◦ DrRacket – Student friendly interface ◦ MIT Scheme – very widely used Query Language Uses statements that are interpreted by the database server. Used with relational databases ◦ Relational databases are based off of first order predicate logic. Used by MS SQL Server database and Sybase database. Main application is the construction and manipulation of enterprise databases. History: ◦ Evolved from SEQUEL. ◦ SEQUEL (Structured English Query Language) is a query language developed by IBM in the 1970’s and they later renamed it to SQL (Structured Query Language) ◦ T-SQL (Transact SQL) is an extension to SQL developed by a partnership between Microsoft and Sybase. Data in relational databases are comprised of entity types Entity Types are collections of the of the entities and thought type and are represented as TABLES. Each instance of that entity is a record or tuple and is represented as a row in the table. Records are comprised of different attributes, and they are represented as columns in the table. T-SQL is technically a data-sublanguage The T-SQL sublanguage is comprised of the following: ◦ Data Definition Language (DDL) ◦ Data Manipulation Language (DML) The DML is used to define database structure, integrity rules, and user privileges. Includes the following commands: ◦ CREATE TABLE, DROP TABLE, ALTER TABLE ◦ CREATE VIEW, DROP VIEW ◦ CREATE INDEX, DROP INDEX The DML is used to manipulate the data within the database. DML Commands Include: ◦ ◦ ◦ ◦ SELECT INSERT UPDATE DELETE T-SQL extends SQL to include: ◦ Procedural Programming ◦ Local Variables ◦ Support functions for processing various data types The extensions included in T-SQL grant it equivalent capabilities to other programming languages. Flow control in T-SQL: ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ ◦ Begin End Break Continue GOTO IF ELSE RETURN WHILE WAITFOR T-SQL contains try-catch blocks, unlike SQL Example: BEGIN TRY //STATEMENTS END TRY BEGIN CATCH //STATEMENTS TO HANDLE EXCEPTION END CATCH T-SQL performs queries and data manipulation very efficiently across a wide variety of data types. Readability: ◦ High overall simplicity. Lack of multiplicity and overloading. ◦ Excellent facilities for defining data types ◦ Form indicates meaning Writability: ◦ More expressive than SQL ◦ Poor Abstraction T-SQL supports a wide variety of primitive data types The primitive data types can be easily combined in tables to easily create new data structures. Type-Checking: ◦ Data must be of the appropriate type for a statement to execute. Exception-Handling: ◦ T-SQL provides for exception handling, unlike SQL. Modularity and portability are a common and touted attribute amongst the languages, but C# achieves this goal to a greater extent than the others. C# does not support shadowing like Scheme does. All three languages are supported crossplatform. I drew the following conclusions my research in to these three languages: ◦ Studying different types of languages increased my ability to select an appropriate language for a given task. ◦ As I learned more languages, I was able to pick up new languages faster. ◦ Due to the similarities between the languages, studying C# improved my knowledge of Java. ◦ Many projects are best implemented through the use of multiple languages.