Writing and Reading Binary data in FORTRAN and C++

[VictorN]

Yes, If I write 12.54 to a binary file ( not console) with FORTRAN and then read that binary file with C++ it works fine. But in thatcase I am using ifstream to read the file and not using ReadFile() function.

Then the problem seems to be with your ReadFile?
Show your complete code for both case: when using ifstream and when using ReadFile