Question

I have this .py 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("?")

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")

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

What I do not understand:

a) Why in the interpreter if I write, raw_input("?"), then type f and press enter, it outputs the 'f' string and if I run the .py file it doesn’t return me the ‘f’ string?

b) Also, python docs says: ” The function then reads a line from input, converts it to a string (stripping a trailing newline), and returns that. So, why does the line 7 gets printed on a new line instead of line 6(“?Opening the file…”). Where is that \n coming from?

Answer 1

a) The interpreter prints the output of the commands by default, but your script doesn’t do that unless you use the print statement.

print raw_input('?')

b) The '\n' isn’t in the string returned from raw_input, but it’s anyway captured by the console when you press enter so this is a side effect you get when using raw_input.

print repr(raw_input('?'))  # You'll get 'f', not 'f\n'