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Convert.ToUInt32 Method (String, Int32)

Converts the string representation of a number in a specified base to an equivalent 32-bit unsigned integer.

This API is not CLS-compliant. 

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

<CLSCompliantAttribute(False)> _
Public Shared Function ToUInt32 ( _
	value As String, _
	fromBase As Integer _
) As UInteger
Dim value As String 
Dim fromBase As Integer 
Dim returnValue As UInteger 

returnValue = Convert.ToUInt32(value, _


Type: System.String

A string that contains the number to convert.

Type: System.Int32

The base of the number in value, which must be 2, 8, 10, or 16.

Return Value

Type: System.UInt32
A 32-bit unsigned integer that is equivalent to the number in value, or 0 (zero) if value is Nothing.


fromBase is not 2, 8, 10, or 16.


value, which represents a non-base 10 unsigned number, is prefixed with a negative sign.


value contains a character that is not a valid digit in the base specified by fromBase. The exception message indicates that there are no digits to convert if the first character in value is invalid; otherwise, the message indicates that value contains invalid trailing characters.


value, which represents a non-base 10 unsigned number, is prefixed with a negative sign.


value represents a number that is less than UInt32.MinValue or greater than UInt32.MaxValue.

If fromBase is 16, you can prefix the number specified by the value parameter with "0x" or "0X".

Because the UInt32 data type supports unsigned values only, the ToUInt32(String, Int32) method assumes that value is expressed using unsigned binary representation. In other words, all 32 bits are used to represent the numeric value, and a sign bit is absent. As a result, it is possible to write code in which a signed integer value that is out of the range of the UInt32 data type is converted to a UInt32 value without the method throwing an exception. The following example converts MinValue to its hexadecimal string representation, and then calls the ToUInt32(String, Int32) method. Instead of throwing an exception, the method displays the message, "0x80000000 converts to 2147483648."

' Create a hexadecimal value out of range of the UInt32 type. 
Dim value As String = Convert.ToString(Integer.MinValue, 16)
' Convert it back to a number. 
   Dim number As UInt32 = Convert.ToUInt32(value, 16)
   Console.WriteLine("0x{0} converts to {1}.", value, number)
Catch e As OverflowException
   Console.WriteLine("Unable to convert '0x{0}' to an unsigned integer.", _
End Try   

When performing binary operations or numeric conversions, it is always the responsibility of the developer to verify that a method or operator is using the appropriate numeric representation to interpret a particular value. The following example illustrates one technique for ensuring that the method does not inappropriately use binary representation to interpret a value that uses two's complement representation when converting a hexadecimal string to a UInt32 value. The example determines whether a value represents a signed or an unsigned integer while it is converting that value to its string representation. When the example converts the value to a UInt32 value, it checks whether the original value was a signed integer. If so, and if its high-order bit is set (which indicates that the original value was negative), the method throws an exception.

' Create a negative hexadecimal value out of range of the UInt32 type. 
Dim sourceNumber As Integer = Integer.MinValue
Dim isSigned As Boolean = Math.Sign(sourceNumber.MinValue) = -1
Dim value As String = Convert.ToString(sourceNumber, 16)
Dim targetNumber As UInt32
   targetNumber = Convert.ToUInt32(value, 16)
   If isSigned And ((targetNumber And &H80000000) <> 0) Then 
      Throw New OverflowException()
      Console.WriteLine("0x{0} converts to {1}.", value, targetNumber)
   End If     
Catch e As OverflowException
   Console.WriteLine("Unable to convert '0x{0}' to an unsigned integer.", _
End Try  
' Displays the following to the console: 
'    Unable to convert '0x80000000' to an unsigned integer.    

The following example attempts to interpret each element in an array of numeric strings as a hexadecimal value and to convert it to an unsigned integer.

Module Example
   Public Sub Main()
      Dim hexStrings() As String = { "80000000", "0FFFFFFF", "F0000000", "00A3000", "D", _
                                     "-13", "9AC61", "GAD", "FFFFFFFFFF" }
      For Each hexString As String In hexStrings
         Console.Write("{0,-12}  -->  ", hexString)
            Dim number As UInteger = Convert.ToUInt32(hexString, 16)
            Console.WriteLine("{0,18:N0}", number)
         Catch e As FormatException
            Console.WriteLine("{0,18}", "Bad Format")
         Catch e As OverflowException
            Console.WriteLine("{0,18}", "Numeric Overflow")
         Catch e As ArgumentException
            Console.WriteLine("{0,18}", "Invalid in Base 16")
         End Try 
   End Sub 
End Module 
'    ' The example displays the following output: 
'    80000000      -->       2,147,483,648 
'    0FFFFFFF      -->         268,435,455 
'    F0000000      -->       4,026,531,840 
'    00A3000       -->             667,648 
'    D             -->                  13 
'    -13           -->  Invalid in Base 16 
'    9AC61         -->             633,953 
'    GAD           -->          Bad Format 
'    FFFFFFFFFF    -->    Numeric Overflow

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0