A common error encountered in C++ projects is "C1083: include file cannot be opened: No such file or directory", which occurs because the compiler cannot find a header file. In this article, we explain in detail the cause, solution, and necessary settings in Visual Studio, especially when the flatbuffers/flatbuffers.h file cannot be found.

❓ What is the C1083 Error?

C1083 is an error code given by the compiler in Visual Studio. The cause of the error is usually related to the following situations:

The header file does not physically exist
An incorrect directory is specified
The path to the header file has not been added to "Include Directories"

Example error:

C1083: 'flatbuffers/flatbuffers.h': No such file or directory

What is FlatBuffers and Why is it Used?

FlatBuffers is a data serialization library developed by Google. It is often preferred for transporting data in game engines, network communication, or performance-oriented applications.

To use FlatBuffers, the library files containing the flatbuffers.h file must be included in the project.

️ Step-by-Step Solution Guide

✅ 1. Add the FlatBuffers Library to the Project

Download the library from GitHub:

https://github.com/google/flatbuffers
After downloading, you should be able to see the flatbuffers.h file in the include/flatbuffers folder

✅ 2. Configure the Include Path in Visual Studio

Right-click on the project > Properties
Go to Configuration Properties > C/C++ > General
Click on the Additional Include Directories option
Add the full path to the flatbuffers folder:

C:\path\to\flatbuffers\include

Save and rebuild the project

✅ 3. Installation via NuGet (Alternative Method)

In some cases, FlatBuffers can also be added via NuGet:

Tools > NuGet Package Manager > Manage NuGet Packages for Solution
Type flatbuffers in the search box
Select the appropriate package and include it in the project

⚠️ Note: Some FlatBuffers versions only contain source. You may need to manually compile and generate a .lib file.

Extra: "E1670: Type qualifier is not allowed on a nonmember function" Error

This error usually occurs because the include process fails. The compiler gives a syntax error because it cannot recognize the flatbuffers namespace. Therefore, this error will not disappear until C1083 is resolved.

Verification and Testing

#include "flatbuffers/flatbuffers.h"

int main() {
    flatbuffers::FlatBufferBuilder builder(1024);
    return 0;
}

This code should compile without any issues if flatbuffers is properly integrated.

✅ Conclusion

Although the C1083 error may seem annoying, it can be easily resolved when you introduce the missing files and correct paths. When working with external libraries such as FlatBuffers, file paths and configuration settings are of great importance. Correctly defining include directories in Visual Studio prevents such errors.