主要是三个函数：fopen fclose load

1. fopen

    fileID = fopen(filename)
    fileID = fopen(filename,permission)
    fileID = fopen(filename,permission,machinefmt,encoding)
    
    %permissions%
    'r': Open file for reading.
    'w': Open or create new file for writing. Discard existing contents, if any.
    'a': Open or create new file for writing. Append data to the end of the file.
    'r+':Open file for reading and writing.
    'w+':Open or create new file for reading and writing. Discard existing contents, if any.
    'a+':Open or create new file for reading and writing. Append data to the end of the file.
    'A' :Open file for appending without automatic flushing of the current output buffer.
    'W' :Open file for writing without automatic flushing of the current output buffer.
    
    %machinefmt — Order for reading or writing bytes or bits%
    Use 'n' for nagtive
    
    %encoding%
    'UTF-8' 'US-ASCII'

在note的开头打开可写的in.txt：

    fopen('in.txt','w+','n','UTF-8');

2.fclose

    fclose(fileID) closes an open file.
    fclose('all') closes all open files.

3.load

    load(filename) loads data from filename.
    load(filename,'-ascii') treats filename as an ASCII file, regardless of the file extension.
    load(filename,'-mat') treats filename as a MAT-file, regardless of the file extension.

在note的开头读取in.txt:

    load('in.txt');

附上example.m:

input = load('in.txt');
out=fopen('out.txt','w+','n','UTF-8');

fprintf(out,'%d',...);
fclose(out);