# module purge;  module load python/2.7.2
# just run it, no compiling, no linking, no libraries

# variable naming convention:  since there are different types it is helpful to append the type to the variable, such as S for a string, File for a file

testFile = open('readtest.txt')	# open() is a built-in function, no import
print type(testFile)			# f is a file object
				#   has data and methods

jS = testFile.readline()	# readline() returns the characters in a line, including newline at end
print type(jS)

print "\n------------------read and print each line of a text file including newline-------------"
while len(jS) > 0:		# len is a built-in function
	print jS
	jS = testFile.readline()
	
testFile.close()

print "\n------------------iterate on file, line by line-------------"
gFile = open("readtest.txt")

for jS in gFile:		# python magic: a text file iterates on lines
	print jS		# python magic:  trailing comma suppresses printing of newline

gFile.seek(0)			# rewind the file


print "\n------------------python magic string slicing-------------"
s = "Now I have a string"
print s
print s[1:7]
print s[0:7]
print s[:7]
print s[8:len(s)]
print s[8:]
print s[8:-1]
print s[8:-2]

print s[0: :2]		# 0: means from the beginning   :2 means every 2nd character

print "\n------------------suppress newline using string slicing-------------"
for j in gFile:
	print j[:-1]		# python magic: slice string from implied beginning to character before last character (which is the newline character)

gFile.close()


print "\n------------------read the file into a list of strings-------------"
gFile = open("readtest.txt")
sL = gFile.readlines()
print type(sL)
print sL


print "\n------------------string concatenation:  magic plus sign-------------"
print sL[2] + sL[1]

a = sL[2]
a = a[:-1]

b = sL[1]
b = b[:-1]
print a + " and " + b + " both on the same line."

gFile.close()

""" this is a multi-line
of text within triple quotes that will be
converted to a string.
It will be compiled but will
not execute anything"""

''' can use single
triple apostrophes
'''