Using fscanf to set a variable in a different class

I'm trying to read a number from a file and set it to a public variable in a different class. The function that is reading the file has a pointer-object instance of that class. I'm facing a weird issue:

The following works:

int dummy;
fscanf(file,"%d",&dummy); // assume the file stores the number 10

globals->var = dummy;

cout << "variable is " << globals->var << endl; // this outputs 10 to console. great!

But I'm going to have a lot of fscanf's to do, and I don't want to create all of these redundant dummy variables. I tried the following:

fscanf(file,"%d",&globals->var);
cout << "variable is " << globals->var << endl; // this outputs 2.9e-321 (aka junk)

Is there a reason that doesn't work? Do I need to do it like globals->&var, or some variation like that? I tried to wrap it in parentheses like so: &(globals->var), but that didn't work either. Is there a reason this is not working (without me having to paste many many many lines of开发者_开发百科 code)

Thanks!

As you said in the comment, the type of var is double. Yes, that is the problem. You should use %f for it.

Apart from that, I would give you a piece of advice:

Prefer using C++ stream for I/O work. They're type-safe. If you use them, you would not face this problem which you faced it with fprintf.

Here is how you should use it:

std::ifstream file("filename.txt");
file >> globals->var; //don't worry about whether var is int, or double!

Cool, isn't it?

The Problem is most probably that globals->var is a float or double convert it to an int or some other integer-type and it should work

The reason why it's outputting "junk" is that float/double numbers are encoded in a special way. If you just overwrite that memory with an perfectly valid integer like:

double value = 0.0;
*((int*)&value) = 42;
// value is now something like 2.07508e-322

you nonetheless get a "strange" number. This is what happens internally in scanf with %d as parameter.