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Get started with C

This guide walks you through the steps to use a code example, and then explains how to integrate the Pdftools SDK into your application with the C programming language.

tip

Try the Pdftools SDK without a license key.

Get started with a sample project​

Learn how to use the Pdftools SDK using a C code example. The Pdf2ImgSimple example converts a PDF file to an image. Use similar steps to run any other code example from the sdk-examples-c repository.

Prerequisites​

This code example uses GCC toolset 4.8+ and CMake version 3.16 or higher.

Compile and run the sample​

  1. Clone the sdk-examples-c repository:

    git clone https://github.com/pdf-tools/sdk-examples-c.git

  2. Navigate to the Pdf2ImgSimple code example:

    cd sdk-examples-c/Pdf2ImgSimple

  3. Configure the project:

    cmake .

  4. Build the sample:

    cmake --build .

  5. The code example contains a PDF file PdfPrimerWhitePaper.pdf. To render it in multi-page TIFF image format, run:

    ./pdftoolspdf2imgsimple PdfPrimerWhitePaper.pdf PdfPrimerWhitePaper.tiff

The sample runs without a license key, and the output carries a watermark. To remove the watermark, open pdftoolspdf2imgsimple.c and uncomment the PdfTools_Sdk_Initialize function call in main(). Replace the "insert-license-key-here" placeholder with your license key. Include the less-than (<) and greater-than (>) signs.

The code example takes:

  • The input and output files are represented as a file name or a file path with the file name.
  • Both file paths (input and output) can be relative or absolute.

Compare the command syntax with a placeholder to the previous procedure:

./pdftoolspdf2imgsimple INPUT_FILE OUTPUT_FILE
note

You can apply a similar procedure described in this tutorial for other code examples. For more information, see Code samples page.

Integrate the SDK into your application​

Integrate and initialize the Pdftools SDK into your application.

Add the SDK to your project​

  1. Click the download link to get the latest version of the Pdftools SDK for C in a zip archive.

    Optional: For older Linux distributions running glibc 2.17+, download the SDK from a separate download.

  2. Unzip the file on your machine into a local directory recommended for your operating system. For example:

    C:\Program Files\PDF Tools AG\

    Included subdirectories are:

    SubdirectoryDescription
    ~Contains important information in the README.md file.
    libRuntime executable binaries and runtime import libraries:
    • win-x86\PdfToolsSdk.dll and win-x86\PdfToolsSdk.lib for 32-bit Windows.
    • win-x64\PdfToolsSdk.dll and win-x64\PdfToolsSdk.lib for 64-bit Windows.
    • win-arm64\PdfToolsSdk.dll and win-arm64\PdfToolsSdk.lib for 64-bit Windows ARM.
    includeHeader files to add to your C or C++ project. The main header PdfTools.h includes all the other headers.

  3. Optional: The native libraries must be available in your compiler’s library path. This step is only required if your build process doesn’t resolve it automatically:

    Add the lib\win-x64, lib\win-arm64 or lib\win-x86 subdirectory to the %PATH% environment variable.

Optional: Initialize the SDK​

Learn how to remove watermarked output of the Pdftools SDK using a valid license key.

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Initialization removes watermarks from output files and readies the SDK for production. Without a license key, output files carry a watermark.

Getting a license key

Contact the Pdftools sales team through the Contact page to get a full license. For more information, review the Pdftools SDK license management.

To remove watermarks, follow these steps:

  1. Find your license key. For more information, review Find the license key.

  2. Call PdfTools_Sdk_Initialize once at application startup, before any other Pdftools SDK function call:

    GOTO_CLEANUP_IF_FALSE_PRINT_ERROR(PdfTools_Sdk_Initialize(_T("YOUR_LICENSE_KEY"), NULL),
                                         _T("Failed to set the license key. %s (ErrorCode: 0x%08x).\n"), szErrorBuff,
                                         PdfTools_GetLastError());

    Replace YOUR_LICENSE_KEY with your license key. Use the license key in the same format you copied it. Include the less-than (<) and greater-than (>) signs.

To get a working reference with the PdfTools_Sdk_Initialize function, follow these steps:

  1. Clone the sdk-examples-c repository and navigate to a sample directory. For example, sdk-examples-c/Pdf2ImgSimple.
  2. Open the main C file and find the commented-out PdfTools_Sdk_Initialize call. For example, the Pdf2ImgSimple C sample includes it in pdftoolspdf2imgsimple.c.
  3. Uncomment the call and replace the "insert-license-key-here" placeholder with your license key.

Uninitialize the SDK​

After processing files with the Pdftools SDK, call PdfTools_Uninitialize to unload the library correctly:

// Uninitialize library
PdfTools_Uninitialize();

Implement your use case​

  • Find more use cases and code examples on the Code samples page.
  • For more technical information about the Pdftools SDK for C, consult the C technical notes.
  • If you need to configure a proxy, review Configure proxy documentation section.