Foxit PDF Editor supports the advanced search function, which enables you to do the following: search a string in a single PDF file, multiple PDF files under a specified folder, PDFs in a PDF portfolio, or a PDF index. When the search finishes, all occurrences will be listed in a tree view. This will allow you to quickly preview the context and jump to specific locations. You can also save the search results as a CSV or PDF file for further reference.
Before doing an advanced search, you can go to File > Preferences > Search to specify search preferences. For more information, please refer to the Search preferences.