# Program to print file contents with line number prepended to each line
# This one writes to a file with the same base name but with ".lst" appended
#
# Matt Bishop, MHI 289I, Fall 2019
#

def main():
	# get file name
	try:
		iname = input("Please enter the name of the file to print: ")
	except EOFError:
		return
	except:
		print("Could not read what you typed")
		return
	# get the listing file name
	# replace extension with ".lst" or append ".lst" to file name
	pos = iname.rfind(".")
	if pos == -1:
		oname = iname + ".lst"
	else:
		oname = iname[0:pos] + ".lst"

	#
	# open input, output files
	#
	try:
		infile = open(iname, 'r')
	except IOError:
		print("Error opening file", iname, "for reading")
		return
	except:
		print("Unknown error")
		return
	try:
		outfile = open(oname, 'w')
	except IOError:
		print("Error opening file", oname, "for writing")
		return
	except:
		print("Unknown error")
		return
	#
	#	line by line, adding line numbers as we go
	#
	# initialize line counter
	lineno = 1;
	# for each line in the file ...
	for line in infile:
		# print the line number, then the line
		outfile.write("%6d. " % lineno)
		outfile.write(line)
		lineno = lineno + 1
	# all done!
	infile.close()
	outfile.close()

main()