BigInteger Explicit Conversion (BigInteger to Double)
Assemblies: System.Runtime.Numerics (in System.Runtime.Numerics.dll)
System.Numerics (in System.Numerics.dll)
The overloads of the Explicit method define the types to which or from which a BigInteger object can be converted. Language compilers do not perform this conversion automatically because it can involve data loss. Instead, they perform the conversion only if a casting operator (in C#) or a conversion function (such as CType or CDbl in Visual Basic) is used.
Because the BigInteger value can be outside the range of the Double data type, this operation is a narrowing conversion. If the conversion is unsuccessful, it does not throw an OverflowException. Instead, if the BigInteger value is less than Double::MinValue, the resulting Double value is Double::NegativeInfinity. If the BigInteger value is greater than Double::MaxValue, the resulting Double value is Double::PositiveInfinity.
The conversion of a BigInteger to a Double may involve a loss of precision. In some cases, the loss of precision may cause the casting or conversion operation to succeed even if the BigInteger value is outside the range of the Double data type. The following example provides an illustration. It assigns the maximum value of a Double to two BigInteger variables, increments one BigInteger variable by 9.999e291, and tests the two variables for equality. As expected, the call to the Equals(BigInteger) method shows that they are unequal. However, the conversion of the larger BigInteger value back to a Double succeeds, although the BigInteger value now exceeds Double::MaxValue.