I am writing an application that can read pdf in C# language. How to implement it, and what APIs need to be used. How to implement this function in other programming languages?

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Answers

If you write a C# project and want to achieve interaction between client and PDF file, you may need a dynamic link library (DLL). It allows client to load PDF files, and do further file processing, such as extraction of PDF file content, annotation of PDF page, and PDF page conversion/duplication/deletion, and so on. XsPDF provides such dynamic link library for C# programming. In addition to reading PDF file, it also supports a series of PDF file manipulations.

Reading PDF in a C# application is may not your full requirements. Please describe your requirements in detail. If you just want to load a PDF file into your program, use the file stream import method. If you want to extract the contents of PDF, then you need other APIs. More things you can do, like to extract text, edit pdf, create signature, and more.

As for other programming languages, do you want to see the differences? Or would you like to see whether other languages can implement PDF reading?