Type Conversion Tables in the .NET Framework

 

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.

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

TypeCan be converted without data loss to
ByteUInt16, Int16, UInt32, Int32, UInt64, Int64, Single, Double, Decimal
SByteInt16, Int32, Int64, Single, Double, Decimal
Int16Int32, Int64, Single, Double, Decimal
UInt16UInt32, Int32, UInt64, Int64, Single, Double, Decimal
CharUInt16, UInt32, Int32, UInt64, Int64, Single, Double, Decimal
Int32Int64, Double, Decimal
UInt32Int64, UInt64, Double, Decimal
Int64Decimal
UInt64Decimal
SingleDouble

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.

TypeCan be converted to
Int32Single
UInt32Single
Int64Single, Double
UInt64Single, Double
DecimalSingle, Double

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 System.Convert class are always checked in this manner.

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

TypeCan be converted to
ByteSByte
SByteByte, UInt16, UInt32, UInt64
Int16Byte, SByte, UInt16
UInt16Byte, SByte, Int16
Int32Byte, SByte, Int16, UInt16,UInt32
UInt32Byte, SByte, Int16, UInt16, Int32
Int64Byte, SByte, Int16, UInt16, Int32,UInt32,UInt64
UInt64Byte, SByte, Int16, UInt16, Int32, UInt32, Int64
DecimalByte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64
SingleByte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64
DoubleByte, SByte, Int16, UInt16, Int32, UInt32, Int64, UInt64

System.Convert
Type Conversion in the .NET Framework

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