This is a free site for programming practice. Complete the code in the browser and submit. Try this example. If your report looks like this, keep on trying until all test cases pass.


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Frequently Asked Questions


Thanks to Chaz Chang from San José State University for implementing the “edit URL” feature that enables instructors to edit problems. Previously, an instructor had to make a new problem to fix any issues with a problem.

Thanks to Greta Yu from Evergreen Valley High School for implementing multiple editable areas. In older versions of CodeCheck, the entire code was in a single text area and it was not possible to protect code from being edited.

Thanks to Anthony Trinh and Hien Vu from San José State University for providing text areas for inputting and editing problems. Previously, it was only possible to upload a zip file.

About This Service

If you have suggestions for improvement, please contact the author, Cay Horstmann (