Error using json.dump();

[Jerajo]

I'm using visual studio and I got this error. on the xutility file

Exception thrown: write access violation.
this was 0xAFE3D714.

I'm doing a "C" compatible DLL in C++. Here is the code:

#define gmx extern "C" __declspec(dllexport)
using json = nlohmann::json;

static json jsonDoc;

gmx double read(char* path) {
	try
	{
		ifstream jsonFile(path);
		jsonFile >> jsonDoc;
	}
	catch (const std::exception& error)
	{
		cout << error.what() << endl;
	}
	return 0;
}

gmx string getJsonFile() {
	return jsonDoc.dump();
}

Then I implement it like this.

_read(file);
string output = _getJsonFile();
cout << output.c_str();

I don't know what I doing wrong. I hope someone can help me.

windows 10 x86 Visual Studio 2017 (v141):
print screen:

[Jerajo]

I do apology for the inconvenience.
I solve the issue was that I was calling the function as char* when I declared it string.