""" Produced by Andrew Jason Penner
    Sept 31 2007
"""
#! /usr/bin/python

""" We may want to try formatted output """

s = 'Hello World'
print 'This is the string s',str(s)

print 'This is another way of producing the string s, note the quotes around the string.',repr(s)

""" repr() returns the litteral, all special characters etc... """

""" This is one way to display a table. rjust(n) justifies the current 
    column to a width of n.
"""
for x in range(1,11):
    print repr(x).rjust(2), repr(x**2).rjust(3),
    print repr(x**3).rjust(4)

""" Here we take on a C style output formatting """
for x in range(1,11):
    print '%2d %3d %4d' %(x,x**2,x**3)

""" zfill(n) looks for n characters in the previous string, failing to find all n, it pads the rest with zeros. If there are more than n characters it does nothing. 
"""
print 'This is the zfill command','12'.zfill(5)

import math
print 'The value of PI is approximately %5.3f.' % math.pi

""" This concludes the section on formating the output, as before there are several other commands but I do not see the need to drone on about it 
"""

""" Now we concern ourselves with reading and writing to files """

""" We see below that the method of opening files is just as we would see in C 
    The first argument is the filename, the second is the mode, w for writing 
    which will clobber an existing file of the same name, r for reading, r+ 
    for reading and writing, a for appending to an existing file. If the mode 
    is omitted, r is assumed.
    On windows and Macs, append b to any of the above for binary files. Linux 
    makes no decision between ascii and binary files.
    Below f is referred to as a file pointer.
"""
f=open('/tmp/workfile','w')

""" a module read(size) appended to an open file will read a quantity of 
    data and returns it as a string. If one omits 'size' the entire file 
    is read. If the end of file is reached it will return an empty string.

    readline reads the lines of the file, one line at a time
    readlines reads all the complete lines in a file, returning them as a list
"""
#f.read()
#f.readline()
#f.readlines()

""" the module write(string) writes the contents of string to a file.
    to write things that are not strings you must convert them to strings 
    first, using str().
"""
#f.write('hello world')

""" Further modules of interest:
	tell() returns an integer giving an object's current position in bytes
	seek(offset,from_object) This function adds offset to the position of 
	from_object. If from_object is 0 it seeks from the beginning of file. 
	If from_object is 1 it uses the current file position (not always a 
	safe option), if from_object is 2 it seeks from the end of file. If 
	from_object is omitted, it defaults to 0.
"""
#f.tell()
#f.seek(5)

""" Finally when one is done with a file you close it using close(). 
    No arguments are necessary. 
"""
#f.close()

""" The last module to be discussed here is pickle
    pickling is the process of converting a nonstring element into a string element (pickle.dump(nonstring,file_pointer))
    to reverse this one is unpickling (pickle.load(file_pointer))
"""
#pickle.dump(x,f)
#pickle.load(f)