(exercise10c)=
# Exercise 10: Write histograms to a file 
**(10 minutes)**

In all the analysis macros we've worked with, we've drawn any plots in
the `Terminate` method. Pick one of your analysis macros that creates
histograms, and revise it so that it does not draw the histograms on the
screen, but writes them to a file instead. Make sure that you don't try
to write the histograms to {file}`experiment.root`; write them to a different
file named {file}`analysis.root`. When you're done, open {file}`analysis.root` in
ROOT and check that your plots are what you expect.

:::{hint}
In {ref}`Saving your work, part 2 <savework2>`, I described all
the commands you're likely to need.

Don't forget to use the ROOT web site as a reference. Here's a question
that's also a bit of a hint: What would be the difference between
opening your new file with "UPDATE" access, "RECREATE" access, and
"NEW" access? Why might it be a bad idea to open a file with "NEW"
access? (A hint within a hint: what would happen if you ran your macro
twice?)
:::