EDP Prefinals

streams

represent a source that provides a sequence of bytes, such as a file, an IO device, an interprocess communication pipe, or a TCP/IP socket

• output streams

• input streams

these are the two types of streams

output streams

refers to a printer, remote server location, or a printer where the data is written

input streams

refers to a file or any source where the data can be read and assigned to the memory variables in the program

System.IO

in C#, the ___ namespace contains classes that allow to write and read files. it needs to be included in all programs that use streams

byte-oriented

all files are ___, meaning the data is written or read into the files in terms of bytes

FileStream

is a class that is used to create a byte-oriented stream attached to a file

FileStream(string filename, FileMode mode)

this is the code to be used for creating a FileStream object

mode

this parameter specifies how the file needs to be opened

FileMode.Create

file mode that creates a new output file, which will be overwritten if a file already exists

FileMode.CreateNew

file mode that creates a new output file that is not existing

FileMode.Open

file mode that opens an existing file

FileMode.OpenOrCreate

file mode that opens an existing file. if not, it creates a new one

FileMode.Truncate

file mode that opens an existing file and truncates the content that already exists

FileStream constructor

this is used to open a file that has access to read or write. it also contains methods to perform read and write operations

ReadByte()

this method reads a single byte from a file and returns as an integer value

Read()

this method reads the specified number of bytes from a file into an array

WriteByte()

method that writes the specified byte into the file

Write()

method that writes an array of bytes into the file

Flush()

this method instantly writes the data into the file

void Close()

this method closes the file, releasing the system resources that are allocated to it

position the file pointer inside the file at the required location

how can we access a file randomly?

file pointer

this determines the location of the next read/write operation to take place on the file

Seek()

this is the method used to relocate the file pointer in the file

Seek()

a method that allows setting the file position indicator of file pointer to the preferred location in the file

long Seek(long n, SeekOrigin Location)

this is the syntax for the Seek() method

Position property of the Stream class

the file pointer can get or set the position using which property?

• CanRead

• CanSeek

• CanTimeout

• CanWrite

• length

• ReadTimeout

• WriteTimeout

aside from the Position property, these 7 properties are commonly used

bool CanRead

this returns true if the stream can be read

bool CanSeek

returns true if the stream supports position requests

bool CanWrite

returns true if the stream can be written

long length

contains the size of the stream

int ReadTimeout

indicates the time before a timeout occurs for read operations

int WriteTimeout

indicates the time before a timeout occurs for write operations

true

(T/F) to perform a character-based file for managing text files, use character streams to read and write into the file

StreamReader, StreamWriter

since, internally, each file consists of bytes, the FileStream is wrapped inside either a ___ or a ___. these classes automatically convert a byte stream into a character stream, and vice versa

StreamWriter

this writes characters to a stream and contains several constructors

StreamWriter(Stream stream)

this StreamWriter constructor is used to create a character-based output stream

StreamWriter(string fileName)

this StreamWriter constructor is used to open a file directly

Close()

this method of the StreamWriter class closes the file

Flush()

this method of the StreamWriter class instantly saves the file content from buffer to memory

Write()

this method of the StreamWriter class writes into the specified file using a File stream class

WriteLine()

this method of the StreamWriter class writes into a file, line by line

StreamReader

is a class that reads characters from a byte stream

StreamReader(Stream stream)

this StreamReader constructor is the name of an open stream such as IO devices or a file

StreamReader(string fileName)

this StreamReader constructor specifies the name of the file to open

Flush()

this method of the StreamReader class instantly saves the file content from buffer to memory

Close()

this method of the StreamReader class closes the file and is mandatory to this class

Read()

this method of the StreamReader class reads the content from the file stream

ReadLine()

this method of the StreamReader class reads the content line by line from the given file stream

ReadToEnd()

this method of the StreamReader class reads all characters from the current location until the end of the stream

Peek()

this method of the StreamReader class returns the value in the stream without moving the file pointer

Seek()

this method of the StreamReader class sets the file pointer at the desired position in a file

assemblies

are files that contain compiled code targeted at the .NET framework

physical packages meant for distributing code

assemblies are basically ___

true

(T/F) the .NET classes are actually contained in several assemblies

• metadata

• manifest

an assembly has two sections, which are?

metadata

includes info about the data types of the program that are being used

manifest

holds the info of the assembly, which consists of the name, version, number, and type of mapping information

• .exe

• .dll

an assembly has two file extensions, which are?

.exe

file extension for standalone applications

.dll

file extension for reusable components

C:\Windows\assembly

the .NET frameworks’ core assemblies location can be found where?

private assembly

simplest type of assembly that can only be used within a software package that is intended to be used                    

no, since the application can only see classes that are mentioned in its private assembly

are two private assemblies with the same class name a problem?

true

(T/F) private assembles do not require registry entries

shared assemblies

are libraries that other applications can commonly use

yes, since any other software can access a shared assembly

are security precautions necessary when using shared assemblies?

name collision

is a common problem in shared assembly wherein other classes or variables have the same name that matches with the other shared assembly

true

(T/F) a different form of the same assembly might overwrite the shared assembly, and the new version might be incompatible with the existing code

shared assemblies are given a strong, unique name based on the private key cryptography

what is done to avoid name collision in shared assemblies?

global assembly cache (GAC)

this enables several applications to share shared assembly

true

(T/F) in GAC, it is required to add the assembly to the special directory

true

(T/F) GAC is the centralized storage location for .NET assemblies`

create a project containing a class file

this is the first step in creating a shared assembly

it contains the methods and properties that you want other applications to access

what does the class file contain?

generate a strong name for the project

this is the second step in creating a shared assembly

ShareAssemblyMessageKeyFile

the strong name for a shared assembly is saved in a strong key filename, such as what?

true

(T/F) the strong key file is created named ShareAssemblyMessageKeyFile.snk and located at the solutions explorer

specify the key filename in the project by indicating its strong key file name in the AssemblyInfo.cs file

this is the third step in creating a shared assembly

compile the project to generate an assembly

this is the fourth and last step in creating a shared assembly

true

(T/F) in compiling the project to generate an assembly, the assembly is generated with the extension .dll