Type Conversion Tables in .NET

Widening conversion occurs when a value of one type is converted to another type that is of equal or greater size. A narrowing conversion occurs when a value of one type is converted to a value of another type that is of a smaller size. The tables in this topic illustrate the behaviors exhibited by both types of conversions.

Widening Conversions

The following table describes the widening conversions that can be performed without the loss of information.

Type Can be converted without data loss to
Byte UInt16, Int16, UInt32, Int32, UInt64, Int64, Single, Double, Decimal
SByte Int16, Int32, Int64, Single, Double, Decimal
Int16 Int32, Int64, Single, Double, Decimal
UInt16 UInt32, Int32, UInt64, Int64, Single, Double, Decimal
Char UInt16, UInt32, Int32, UInt64, Int64, Single, Double, Decimal
Int32 Int64, Double, Decimal
UInt32 Int64, UInt64, Double, Decimal
Int64 Decimal
UInt64 Decimal
Single Double

Some widening conversions to Single or Double can cause a loss of precision. The following table describes the widening conversions that sometimes result in a loss of information.

Type Can be converted to
Int32 Single
UInt32 Single
Int64 Single, Double
UInt64 Single, Double
Decimal Single, Double

Narrowing Conversions

A narrowing conversion to Single or Double can cause a loss of information. If the target type cannot properly express the magnitude of the source, the resulting type is set to the constant PositiveInfinity or NegativeInfinity. PositiveInfinity results from dividing a positive number by zero and is also returned when the value of a Single or Double exceeds the value of the MaxValue field. NegativeInfinity results from dividing a negative number by zero and is also returned when the value of a Single or Double falls below the value of the MinValue field. A conversion from a Double to a Single might result in PositiveInfinity or NegativeInfinity.

A narrowing conversion can also result in a loss of information for other data types. However, an OverflowException is thrown if the value of a type that is being converted falls outside of the range specified by the target type's MaxValue and MinValue fields, and the conversion is checked by the runtime to ensure that the value of the target type does not exceed its MaxValue or MinValue. Conversions that are performed with the Convert class are always checked in this manner.

The following table lists conversions that throw an OverflowException using Convert or any checked conversion if the value of the type being converted is outside the defined range of the resulting type.

Type Can be converted to
Byte SByte
SByte Byte, UInt16, UInt32, UInt64
Int16 Byte, SByte, UInt16
UInt16 Byte, SByte, Int16
Int32 Byte, SByte, Int16, UInt16,UInt32
UInt32 Byte, SByte, Int16, UInt16, Int32
Int64 Byte, SByte, Int16, UInt16, Int32,UInt32,UInt64
UInt64 Byte, SByte, Int16, UInt16, Int32, UInt32, Int64
Decimal Byte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64
Single Byte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64
Double Byte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64

See Also

Convert
Type Conversion in .NET