LPTHW_ex16

# close -- closes the file
# read -- reads the contents of the file, you can assign the result to a variable.
# readline -- reads just one line of a text file
# truncate -- empties the file
# write(stuff) -- writes stuff to the file

from sys import argv

script, filename=argv

print "We're going to erase %r." % filename
print "If you don't want that, hit CTRL-C (^C)."
print "If you do want that, hit RETURN."

raw_input("?")

###?Traceback (most recent call last):
###  File "ex16.py", line 15, in <module>
###    raw_input("?")
### KeyboardInterrupt


print "Opening the file..."
target=open(filename, 'w')

print "Truncating the file. Goodbye!"
#target.truncate()

print "Now I'm going to ask you for three lines."

line1=raw_input("line 1: ")
line2=raw_input("line 2: ")
line3=raw_input("line 3: ")

print "I'm going to write these to the file."

# target.write(line1)
# target.write("\n")
# target.write(line2)
# target.write("\n")
# target.write(line3)
# target.write("\n")

# ec.3 : b=line1+'\n'+line2+'\n'+line3
# ec.4 : target.write(b)

target.write(line1+'\n'+line2+'\n'+line3)

print "And finally, we close it."
target.close()



## extra credit
# Write a script similar to the last exercise that uses read and argv to read the file you just created.
# There's too much repetition in this file. Use strings, formats, and escapes to print out line1, line2, and line3 with just one target.write() command instead of 6.
# Find out why we had to pass a 'w' as an extra parameter to open. Hint: open tries to be safe by making you explicitly say you want to write a file.
# If you open the file with 'w' mode, then do you really need the target.truncate()? Go read the docs for Python's open function and see if that's true.