Learn file concepts in python - Read time - 5 mins!!

file_concepts.py

#!/usr/bin/env python

# Just for practicing the file operation in python


def file_basics():
    print ' File Operations\n', '*' * 80

    types_of_file = """
    Text Files represent content as normal str strings, perform unicode and decoding automatically (plain)
    Examples: .txt is a plain file
    Binary Files represent content as special bytes string type and allows program to access the content unaltered \n
    Example: .wav, .exe, .mp3 all are binary files
    (Python handles both 8-bit text and binary data and a special string type)
    """
    print types_of_file

    # Handling Text Files

    # Writing the content to a new file
    myfile = open('myfile.txt', 'w')
    myfile.write('hello text file \n')
    myfile.write(types_of_file)
    myfile.write('\n good bye, sweet dreams :P sleep tight \n')
    myfile.flush()      # Writes the content from the buffer (OS) to the disc
    myfile.close()

    print '- - ' * 25
    # Reading the Content from the file
    myfile = open('myfile.txt', 'r')  # Default 'r'  read mode only
    print myfile.readline()
    print myfile.readline()     # Reading line by line
    print myfile.readline()
    myfile.close()

    print '- - ' * 25

    # Reading all at once
    content = open('myfile.txt').read()
    print content.rstrip()

    print '= = ' * 25
    # Reading the file content using the iterator
    for line in open('myfile.txt'):
        print line

    print '= = ' * 25

    print r'c:\Python33\Lib\pdb.py'    # Raw String as a input

    # Handling Binary Files
    with open('data.bin', 'wb') as bin_file:
        bin_file.write('\\x00\\x00\\x00\\x07spam\\x00\\x08')

    data = open('data.bin', 'rb').read()
    print "Binary data = ", data

    print eval('[1, 2, 4]')  # eval() converts the string into any object type


def lib_pickle():
    print "\n Pickle is used to dump the any objects into a file \n", '_' * 80

    F = open('datafile.pk1', 'wb')
    D = {'a': 1, 'b': 2}

    import pickle
    pickle.dump(D,F)
    F.close()

    F = open('datafile.pk1', 'rb')
    E = pickle.load(F)
    print E
    F.close()
    print "\n actual dump is ", open('datafile.pk1', 'rb').read()
    F.close()


def lib_struct():
    print "\n struct is used to pack and unpack the binary files \n", '_' * 80

    print 'Writing the Data'
    F = open('data.bin', 'wb')
    import struct
    data = struct.pack('>i4sh', 7, b'spam', 8)
    print data
    F.write(data)
    F.close()

    print "\n Reading the data"
    F = open('data.bin', 'rb')
    data = F.read()
    print data
    values = struct.unpack('>i4sh', data)
    print values
    F.close()


def main():
    file_basics()
    lib_pickle()
    lib_struct()

    
if __name__ == '__main__':
    main()