:sig
f64 DValue::to_f64(f64 default_value = 0) const

:params
f64 : fallback returned when conversion is not possible
return value : converted value or the fallback

:see
0_DValue
2_DValue_get_by_path

:content
Converts strings, f64, bool, pointer, and single-value maps to a finite double. Invalid or empty strings return the default.

```cpp
f64 price = row["price"].to_f64();
```