How to pass float value to function taking double as reference value

Question

I have a function whose prototype looks like this:

void example (double &var);

But, my problem is I might require to call function with some float values as well. e.g.

float temp=10.1;

example(temp)

If I do this my code don't compile, probably because of passing float value to double reference variable.

I want to avoid writing the overloaded function for double and float.

Can someone please suggest a cleaner/better way to implement this?

Function is basically a truncate function that truncate the input given & yes the original is modified.

Thank you.

Answer 1

How about a template function?

template <typename T>
void example (T &var);

The compiler will replace both float and double usages (keep in mind C++ templates are macros with type-safety)

Answer 2

Passing small types by reference is not recommended. You'd better have something like double example(double var);. That will solve your problem as well.

before:

void example(double& d);

double d = ...;
example(d); // unclear if d was modified

after:

double example(double d);

double d = ...;
d = example(d);

float f = ...;
f = static_cast<float>( example(f) ); // cast required to tell the compiler to allow
                                       // the precision loss