Using C # To read and write files

Source: Internet
Author: User

To read an object, follow these steps:

1. Declare and use the openread of file to instantiate a file stream object, as shown below:

2. Prepare a byte array for storing the file content. fs. length will get the actual size of the file, as shown below:

3. Start reading. Call a method of a file stream to read data into the data array.

Filestream FS = file. openread (filename); or filestream FS = filestream (filename, filemode. open, fileaccess. read, fileshare. read); byte [] DATA = new byte [FS. length]; FS. read (data, 0, Data. length );

The following method provides a safer method than the preceding method to ensure that the file is fully read.

Public static void saferead (Stream stream, byte [] data) {int offset = 0; int remaining = data. length; // read the while (remaining> 0) {int READ = stream as long as the remaining bytes exist. read (data, offset, remaining); If (read <= 0) throw new endofstreamexception ("File Read to" + read. tostring () + "failed! "); // Reduce the remaining bytes remaining-= read; // increase offset + = read ;}}

In some cases, you do not know the actual length of the stream, such as the network stream. In this case, you can use a similar method to read the stream until the data in the stream is fully read. We can initialize a cache first, and then write the stream information read from the stream to the memory stream, as shown below:

Public static byte [] readfully (Stream stream) {// initialize a 32 K cache byte [] buffer = new byte [32768]; using (memorystream MS = new memorystream ()) {// After the returned results are returned, the dispose method of the object will be automatically recycled to release the memory. // The while (true) {int READ = stream will be read continuously. read (buffer, 0, buffer. length); // you can return the result if (read <= 0) return ms until the final 3 M data is read. toarray (); Ms. write (buffer, 0, read );}}}

Although the above examples are relatively simple and the results are not very obvious (most of them are correct), you may have been there for a long time. It doesn't matter this article.ArticleIt was originally intended for beginners. The following method provides a way to read a stream by specifying the cache length, although in many cases you can directly use stream. length indicates the length of the stream, but not all streams can.

Public static byte [] read2buffer (Stream stream, int bufferlen) {// if the specified buffer length is invalid, specify a default length as the cache size if (bufferlen <1) {bufferlen = 0x8000;} // initialize a cache zone byte [] buffer = new byte [bufferlen]; int READ = 0; int block; // read the cached data from the stream each time, knowing that the while (Block = stream. read (buffer, read, buffer. length-read)> 0) {// reset the read location read + = block; // check whether the cache is reached, check whether there is any information that can be read if (read = buffer. length ){ // Try to read a byte int nextbyte = stream. readbyte (); // If the read fails, the result can be returned if (nextbyte =-1) {return buffer ;} // adjust the array size to continue reading byte [] newbuf = new byte [buffer. length * 2]; array. copy (buffer, newbuf, buffer. length); newbuf [read] = (byte) nextbyte; buffer = newbuf; // buffer is a reference (pointer ), this is intended to reset the buffer pointer to a larger memory read ++;} // If the cache is too large, use ret to shrink the buffer read while before, then return byte [] ret = new byte [read]; array. copy (buffer, RET, read); return ret;} using system; using system. io; using system. collections; namespace textfilereader_csharp {class class1 {static void main (string [] ARGs) {streamreader objreader = new streamreader ("C: \ test.txt"); string Sline = ""; arraylist arrtext = new arraylist (); While (Sline! = NULL) {Sline = objreader. Readline (); If (Sline! = NULL) arrtext. Add (Sline);} objreader. Close (); foreach (string soutput in arrtext) console. writeline (soutput); console. Readline ();}}}


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