Matlab中你不熟悉的---读写二进制数据

森之张卫东

读写二进制数据

在本例中显示的脚本文件创建了一个含有10000个随机数的数组，以只写方式打开一个自定义文件，用64位浮点数格式把这个数据写入磁盘，并关闭文件。程序打开所要读取的文件，并读取数组，得到一个100×100的数组。它用来说明二进制I/O操作。

% Script file: binary_io.m

%

% Purpose:

% To illustrate the use of binary i/o functions.

%

% Record of revisions:

% Date Programmer Description of change

% ==== ========== =====================

% 12/19/98 S. J. Chapman Original code

%

% Define variables:

% count                 --Number of values read / written

% fid                   --File id

% filename              --File name

% in_array              --Input array

% msg                   --Open error message

% out_array             --Output array

% status                --Operation status

% Prompt for file name

filename = input('Enter file name: ','s');

% Generate the data array

out_array = randn(1,10000);

% Open the output file for writing.

[fid,msg] = fopen(filename,'w');

% Was the open successful?

if fid > 0

    % Write the output data.

    count =fwrite(fid,out_array,'float64');

    % Tell user

    disp([int2str(count) 'values written...']);

    % Close the file

    status = fclose(fid);

else

    % Output file open failed. Display message.

    disp(msg);

end

% Now try to recover the data. Open the

% file for reading.

[fid,msg] = fopen(filename,'r');

% Was the open successful?

if fid > 0

    % Read the input data.

    [in_array, count] =fread(fid,[100 100],'float64');

    % Tell user

    disp([int2str(count) 'values read...']);

    % Close the file

    status = fclose(fid);

else

    % Input file open failed.Display message.

    disp(msg);

end

当这个程序运行时，结果如下

>> binary_io

Enter file name: testfile

10000 values written...

10000 values read...

在当前目录下，有一个80000字节的文件testfile被创建，这个文件之所以占80000个字节，是因为它含有10000个64位的值，每一个值占8个字节。

森之张卫东

1. % Script file: binary_io.m
   
2. %
   
3. % Purpose:
   
4. % To illustrate the use of binary i/o functions.
   
5. %
   
6. % Record of revisions:
   
7. % Date Programmer Description of change
   
8. % ==== ========== =====================
   
9. % 12/19/98 S. J. Chapman Original code
   
10. %
    
11. % Define variables:
    
12. % count                 -- Number of values read / written
    
13. % fid                   -- File id
    
14. % filename              -- File name
    
15. % in_array              -- Input array
    
16. % msg                   -- Open error message
    
17. % out_array             -- Output array
    
18. % status                -- Operation status
    
19. % Prompt for file name
    
20. filename = input('Enter file name: ','s');
    
21. % Generate the data array
    
22. out_array = randn(1,10000);
    
23. % Open the output file for writing.
    
24. [fid,msg] = fopen(filename,'w');
    
25. % Was the open successful?
    
26. if fid > 0
    
27.     % Write the output data.
    
28.     count = fwrite(fid,out_array,'float64');
    
29.     % Tell user
    
30.     disp([int2str(count) ' values written...']);
    
31.     % Close the file
    
32.     status = fclose(fid);
    
33. else
    
34.     % Output file open failed. Display message.
    
35.     disp(msg);
    
36. end
    
37. % Now try to recover the data. Open the
    
38. % file for reading.
    
39. [fid,msg] = fopen(filename,'r');
    
40. % Was the open successful?
    
41. if fid > 0
    
42.     % Read the input data.
    
43.     [in_array, count] = fread(fid,[100 100],'float64');
    
44.     % Tell user
    
45.     disp([int2str(count) ' values read...']);
    
46.     % Close the file
    
47.     status = fclose(fid);
    
48. else
    
49.     % Input file open failed. Display message.
    
50.     disp(msg);
    
51. end
    

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