How do I copy a string to the clipboard?

Actually, pywin32 and ctypes seem to be an overkill for this simple task. tkinter is a cross-platform GUI framework, which ships with Python by default and has clipboard accessing methods along with other cool stuff.

If all you need is to put some text to system clipboard, this will do it:

from tkinter import Tk # in Python 2, use "Tkinter" instead 
r = Tk()
r.withdraw()
r.clipboard_clear()
r.clipboard_append('i can has clipboardz?')
r.update() # now it stays on the clipboard after the window is closed
r.destroy()

And that's all, no need to mess around with platform-specific third-party libraries.

If you are using Python 2, replace tkinter with Tkinter.

I didn't have a solution, just a workaround.

Windows Vista onwards has an inbuilt command called clip that takes the output of a command from command line and puts it into the clipboard. For example, ipconfig | clip.

So I made a function with the os module which takes a string and adds it to the clipboard using the inbuilt Windows solution.

import os
def addToClipBoard(text):
    command = 'echo ' + text.strip() + '| clip'
    os.system(command)

# Example
addToClipBoard('penny lane')

# Penny Lane is now in your ears, eyes, and clipboard.

As previously noted in the comments however, one downside to this approach is that the echo command automatically adds a newline to the end of your text. To avoid this you can use a modified version of the command:

def addToClipBoard(text):
    command = 'echo | set /p nul=' + text.strip() + '| clip'
    os.system(command)

If you are using Windows XP it will work just following the steps in Copy and paste from Windows XP Pro's command prompt straight to the Clipboard.

You can use pyperclip - cross-platform clipboard module. Or Xerox - similar module, except requires the win32 Python module to work on Windows.

You can use the excellent pandas, which has a built in clipboard support, but you need to pass through a DataFrame.

import pandas as pd
df=pd.DataFrame(['Text to copy'])
df.to_clipboard(index=False,header=False)