:sig
f64 float_val(String s)

:params
s : string to be converted
return value : a f64 containing the number (0 if no number could be identified).

:see
>string
int_val
0_String

:content
Extracts a floating point number from a `String`.

If no usable number can be identified, the result is `0`.

:example
print(float_val("3.14") + 1.0, "\n");
