[Floating point precision](#floating-point-precision)<br>
Catch needs to be able to convert types you use in assertions and logging expressions into strings (for logging and reporting purposes).
Most built-in or std types are supported out of the box but there are two ways that you can tell Catch how to convert your own types (or other, third-party types) into strings.
## operator << overload for std::ostream
This is the standard way of providing string conversions in C++ - and the chances are you may already provide this for your own purposes. If you're not familiar with this idiom it involves writing a free function of the form:
```cpp
std::ostream& operator << ( std::ostream& os, T const& value ) {
os <<convertMyTypeToString(value);
return os;
}
```
(where ```T``` is your type and ```convertMyTypeToString``` is where you'll write whatever code is necessary to make your type printable - it doesn't have to be in another function).
You should put this function in the same namespace as your type, or the global namespace, and have it declared before including Catch's header.
## Catch::StringMaker specialisation
If you don't want to provide an ```operator <<``` overload, or you want to convert your type differently for testing purposes, you can provide a specialization for `Catch::StringMaker<T>`:
```cpp
namespace Catch {
template<>
struct StringMaker<T> {
static std::string convert( T const& value ) {
return convertMyTypeToString( value );
}
};
}
```
## Catch::is_range specialisation
As a fallback, Catch attempts to detect if the type can be iterated
(`begin(T)` and `end(T)` are valid) and if it can be, it is stringified
as a range. For certain types this can lead to infinite recursion, so
it can be disabled by specializing `Catch::is_range` like so:
```cpp
namespace Catch {
template<>
struct is_range<T> {
static const bool value = false;
};
}
```
## Exceptions
By default all exceptions deriving from `std::exception` will be translated to strings by calling the `what()` method. For exception types that do not derive from `std::exception` - or if `what()` does not return a suitable string - use `CATCH_TRANSLATE_EXCEPTION`. This defines a function that takes your exception type, by reference, and returns a string. It can appear anywhere in the code - it doesn't have to be in the same translation unit. For example:
```cpp
CATCH_TRANSLATE_EXCEPTION( MyType const& ex ) {
return ex.message();
}
```
## Enums
> Introduced in Catch2 2.8.0.
Enums that already have a `<<` overload for `std::ostream` will convert to strings as expected.
If you only need to convert enums to strings for test reporting purposes you can provide a `StringMaker` specialisations as any other type.
However, as a convenience, Catch provides the `REGISTER_ENUM` helper macro that will generate the `StringMaker` specialisation for you with minimal code.
