Operation file file class method

File operations

File.Copy(“source”, “targetFileName”, true);// A copy of a document ,true Indicates when the file exists “ Cover ”, If not true, There is an exception in the file .

File.Exists();// Judge whether the file exists

File.Move(“source”,“target”);// Move （ shear ）, Think about how to rename a file ？ The file can be cut across disks .

File.Delete(“path”);// Delete . If the file doesn't exist ？ non-existent , Don't complain

File.Create(“path”);// create a file

File.ReadAllLines(“path”,Encoding.Default);// Read all lines , return string[]
File.ReadAllText(“path”,Encoding.Default);// Read all text return string
File.ReadAllBytes(“path”);// Read the file , return byte[], Treat files as binary .
l===========================================
File.WriteAllLines(“path”,new string[4] ,Encoding.Default);// take string Array writes to file by line .
File.WriteAllText(“path”,“string”);// Write all strings to file
File.WriteAllBytes(“path”,newbyte[5]);// take byte[] Write all to file
File.AppendAllText()// take string Append to file

File stream operation

FileStream fs=File.Open(); // return FileStream 
FileStream fs=File.OpenRead();// Returns a read-only FileStream
FileStream fs=File.OpenWrite();// Return write only FileStream
FileStream fs=new FileStream( Parameters );

Stream（ The parent of all streams , Is an abstract class .）
The classes of file operations are all in System.IO.*;

There are two ways to copy files ： Read all the contents of the source file into memory , Then write to the target file ; Read the... Of the source file 1KB Memory , Write to the target file , Then read the source file 1KB Memory , Then write to the target file ……. The second method is a flow operation .

l use File.ReadAllText、File.WriteAllText File read / write is a one-time read 、 Write , If the file is very large, it will occupy memory 、 slow . Need to read one line and process one line , This is flow (Stream).Stream Only the required position will be read 、 The length of the content .

Stream Not all contents will be read into memory at one time , There's a pointer , Where does the pointer point to read 、 Where to write .

There are many kinds of streams , File stream is one of them .FileStream class newFileStream(“c:/a.txt”, filemode,fileaccess) The optional values and meanings of the last two parameters can be seen by yourself .FileStream Can read but write . have access to File.OpenRead、 File.OpenWrite These two simplified call methods .

byte[] Is the most fundamental representation of any data , Any data is ultimately binary .

FileStream Of Position Property is the current file pointer position , Move every time you write Position In case you write to the next position .Write Used to write several bytes to the current position ,Read The user reads several bytes .

Use FileStream Write text file .
adopt FileStream Write read text file . For Chinese, if every time you read 1 individual byte What's the effect ？ Better choice →StreamReader
Use FileStream Read text file .
Use FileStream Make large file copies .
File.ReadAllBytes() And File.WriteAllBytes() Copy files .（ View memory usage ）
Use using It can easily release resources ( Automatically call Dispose Method )
Only when IDispose Interface can be used using Release resources  

Stream Treat everything as binary , If it's text content , Programmers are required to handle the conversion between text and binary .
use StreamWriter Can simplify the text type Stream To deal with
StreamWriter Is the auxiliary Stream Processed
 using (StreamWriter writer = new StreamWriter(stream, encoding))
 {
      writer.WriteLine(" Hello ");
 }


and StreamWriter similar , StreamReader Simplified reading of text type streams .
 Stream stream = File.OpenRead("c:/1.txt");
   using (StreamReader reader = new StreamReader(stream,encoding))
            {
                //Console.WriteLine(reader.ReadToEnd());
                Console.WriteLine(reader.ReadLine());
            }
ReadToEnd Used to read from the current position to the end , If the content is large, it will occupy memory ; Every call goes down , Cannot be inadvertently called twice
ReadLine Read a line , If it comes to the end , Then return to null.

The cause of garbled code （ Only text files are garbled ）： The encoding used when storing text files , It is inconsistent with the encoding used in reading , It will cause garbled code problem . solve ： Using uniform coding is ok.

Text file code , There are different ways to store text files , In what form is the string saved as binary , This is the code ,UTF-8、ASCII、Unicode etc. , Such as If there is a garbled code, it is usually a coding problem , Text file related functions generally have a Encoding Parameters of type , How to get the encoding ：Encoding.Default、 Encoding.UTF8、Encoding.GetEncoding("GBK")

File encoding （ clock ）

•ASCII: English code table , Each character takes 1 Bytes .

•GB2312： compatible ASCII, Including Chinese . Each English takes up one byte （ Positive numbers ）, Chinese takes up two bytes （ negative ）

•GBK： Simplified Chinese , compatible gb2312, Contains more Chinese characters . English 1 Bytes （ Positive numbers ）, Chinese accounts for two （1 Negative numbers ,1 One can be positive or negative ）

•Big5： Traditional Chinese

•Unicode： International code table , Both Chinese and English 2 Bytes .

•UTF-8： International code table , English 1 Bytes , Chinese accounts for 3 Bytes .l Output Encoding.GetEncodings(), All codes .

What is a text file . What you can still read when you drag it into Notepad is a text file ,doc No .

File Class ：(FileInfo*)

•voidAppendAllText(string path, string contents), Put text contents Attach to file path in

•bool Exists(string path) Judge documents path Whether there is

•string[]ReadAllLines(string path) Read the text file into the string array

•stringReadAllText(string path) Read text file into string

•voidWriteAllText(string path, string contents) Put text contents Save to file path in , Will overwrite the old content .

•WriteAllLines(string path,string[] contents), Save the string array line by line to a file path in , Will overwrite the old content .

Binary negation for positive numbers , add 1 Is the binary of negative numbers .
Encoding.Default

System.Text.DBCSCodePageEncoding Double byte character set . If the output EncodingName Words , The result is ： Simplified Chinese (gb2312)

Encoding.Default: Current with the operating system “ Regional and language options ” of .

 

 

 

  If no code is provided in the system , You can use the GetEncoding(" The encoded value string represents ") Get the code .

            //Encodingencoding=Encoding.GetEncoding("gb2312");

 

            StringBuildersb =newStringBuilder();

            EncodingInfo[]infos = System.Text.Encoding.GetEncodings();

            for(inti = 0; i < infos.Length; i++)

            {

                sb.Append(infos[i].CodePage +"   "+ infos[i].DisplayName +"   "+ infos[i].Name +"\r\n");

            }

 

            File.WriteAllText("encodings.txt",sb.ToString());

 

original text ：

http://blog.csdn.net/n1g2q2012/article/details/9380911

Similar reference ：

http://www.cnblogs.com/zysbk/archive/2012/08/09/2629589.html （ recommend , Graphic version ）