@Matt-Long said:
I am new to Notepad++ and I am trying to write a script to convert 12 hour time into 24 hour time format. Below is the data string that I have to convert:

01-May-26 12:15:00 AM,689.1,WESTHAMPTON_HALL_Elec

This is just one string out of 600+ but I ultimately need them all to read like:

5/1/2026 00:15,689.1,WESTHAMPTON_HALL_Elec

The Timestamps… command in the Columns++ plugin can help with this.

For conversion you want, you would select day-month-year in the From date and time section, then select Custom in the To date and time section, enter M/d/yyyy HH:mm as the custom picture, check Overwrite selection, then click To Date/Time to perform the conversion.

To use this, you need to have all the timestamps lined up in a column and make a column selection. If your document has a series of lines like the example you gave with all three-character months, you can select it as is.

If you have months spelled out, so that the right edge of the column doesn’t line up, you can use a regular expression to change the first comma to a tab, enable Elastic tabstops on the Columns++ menu, and then you can select the column, perform the conversion, and use another regular expression to convert the tabs back to commas. (Alternatively, if this is a CSV file, you can use the Conversion functions in Columns++ to convert from comma separated values to tabs and back again instead of using regular expressions.)

If the timestamps don’t occur in contiguous column at all, we might have to devise a more inventive method of getting them into a column selection if you want to use Columns++ to do the conversion.

For an explanation of how to make a column selection, see:
https://npp-user-manual.org/docs/editing/#entering-column-mode

For an explanation of how to install a plugin from the plugins list (Columns++ is in the list), see:
https://npp-user-manual.org/docs/plugins/#install-using-plugins-admin