Converts the string representation of a number in a specified base to an equivalent 32-bit signed integer.
Assembly: mscorlib (in mscorlib.dll)
Public Shared Function ToInt32 ( _ value As String, _ fromBase As Integer _ ) As Integer
Dim value As String Dim fromBase As Integer Dim returnValue As Integer returnValue = Convert.ToInt32(value, _ fromBase)
public static int ToInt32( string value, int fromBase )
public: static int ToInt32( String^ value, int fromBase )
public static function ToInt32( value : String, fromBase : int ) : int
Parameters
- value
- Type: System.String
A string that contains the number to convert.
- fromBase
- Type: System.Int32
The base of the number in value, which must be 2, 8, 10, or 16.
Return Value
Type: System.Int32A 32-bit signed integer that is equivalent to the number in value, or 0 (zero) if value is null.
| Exception | Condition |
|---|---|
| ArgumentException |
fromBase is not 2, 8, 10, or 16. -or- value, which represents a non-base 10 signed number, is prefixed with a negative sign. |
| FormatException |
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. |
| OverflowException |
value, which represents a non-base 10 signed number, is prefixed with a negative sign. -or- value represents a number that is less than Int32.MinValue or greater than Int32.MaxValue. |
If fromBase is 16, you can prefix the number specified by the value parameter with "0x" or "0X".
Because the negative sign is not supported for non-base 10 numeric representations, the ToInt32(String, Int32) method assumes that negative numbers use two’s complement representation. In other words, the method always interprets the highest-order binary bit of an integer (bit 31) as its sign bit. As a result, it is possible to write code in which a non-base 10 number that is out of the range of the Int32 data type is converted to an Int32 value without the method throwing an exception. The following example increments Int32.MaxValue by one, converts the resulting number to its hexadecimal string representation, and then calls the ToInt32(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 Integer type. Dim value As String = Convert.ToString(CLng(Integer.MaxValue) + 1, 16) ' Convert it back to a number. Try Dim number As Integer = Convert.ToInt32(value, 16) Console.WriteLine("0x{0} converts to {1}.", value, number) Catch e As OverflowException Console.WriteLine("Unable to convert '0x{0}' to an integer.", value) End Try
// Create a hexadecimal value out of range of the Integer type. string value = Convert.ToString((long) int.MaxValue + 1, 16); // Convert it back to a number. try { int number = Convert.ToInt32(value, 16); Console.WriteLine("0x{0} converts to {1}.", value, number.ToString()); } catch (OverflowException) { Console.WriteLine("Unable to convert '0x{0}' to an integer.", value); }
// Create a hexadecimal value out of range of the integer type. String^ value1 = Convert::ToString((static_cast<__int64>(int::MaxValue)) + 1, 16); // Convert it back to a number. try { int number = Convert::ToInt32(value1, 16); Console::WriteLine("0x{0} converts to {1}.", value1, number); } catch (OverflowException ^e) { Console::WriteLine("Unable to convert '0x{0}' to an integer.", value1); } // The example displays the following output: // 0x80000000 converts to -2147483648.
When performing binary operations or numeric conversions, it is always the responsibility of the developer to verify that a method is using the appropriate numeric representation to interpret a particular value. As the following example illustrates, you can ensure that the method handles overflows appropriately by first retrieving the sign of the numeric value before converting it to its hexadecimal string representation. Throw an exception if the original value was positive but the conversion back to an integer yields a negative value.
' Create a hexadecimal value out of range of the Integer type. Dim sourceNumber As Long = CLng(Integer.MaxValue) + 1 Dim isNegative As Boolean = (Math.Sign(sourceNumber) = -1) Dim value As String = Convert.ToString(sourceNumber, 16) Dim targetNumber As Integer Try targetNumber = Convert.ToInt32(value, 16) If Not isNegative And ((targetNumber And &H80000000) <> 0) Then Throw New OverflowException() Else Console.WriteLine("0x{0} converts to {1}.", value, targetNumber) End If Catch e As OverflowException Console.WriteLine("Unable to convert '0x{0}' to an integer.", value) End Try ' Displays the following to the console: ' Unable to convert '0x80000000' to an integer.
// Create a hexadecimal value out of range of the Integer type. long sourceNumber = (long) int.MaxValue + 1; bool isNegative = Math.Sign(sourceNumber) == -1; string value = Convert.ToString(sourceNumber, 16); int targetNumber; try { targetNumber = Convert.ToInt32(value, 16); if (!(isNegative) & (targetNumber & 0x80000000) != 0) throw new OverflowException(); else Console.WriteLine("0x{0} converts to {1}.", value, targetNumber); } catch (OverflowException) { Console.WriteLine("Unable to convert '0x{0}' to an integer.", value); } // Displays the following to the console: // Unable to convert '80000000' to an integer.
__int64 sourceNumber2 = (static_cast<__int64>(int::MaxValue)) + 1; bool isNegative = Math::Sign(sourceNumber2) == -1; String^ value2 = Convert::ToString(sourceNumber2, 16); int targetNumber; try { targetNumber = Convert::ToInt32(value2, 16); if (!(isNegative) & (targetNumber & 0x80000000) != 0) throw gcnew OverflowException(); else Console::WriteLine("0x{0} converts to {1}.", value2, targetNumber); } catch (OverflowException ^e) { Console::WriteLine("Unable to convert '0x{0}' to an integer.", value2); } // The example displays the following output: // Unable to convert '0x80000000' to an integer.
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.