C++ Syntax to upload excel or text data to C++ and also to write data from C++

Hi,

Can anyone help with the C++ syntax to read in data of type double from an excel spread sheet file or from a notepad txt file. I have develop this code that is running for a kernel density estimation model but i need to upload my data to the main code and write the result after processing to another txt or excel file.

Cheers,
Kemi:|