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Convert.ToInt16 Method (String, Int32)

Converts the string representation of a number in a specified base to an equivalent 16-bit signed integer.

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

public static short ToInt16(
	string value,
	int fromBase
)

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.Int16
A 16-bit signed integer that is equivalent to the number in value, or 0 (zero) if value is null.

ExceptionCondition
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 Int16.MinValue or greater than Int16.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 ToInt16(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 15) 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 Int16 data type is converted to an Int16 value without the method throwing an exception. The following example increments Int16.MaxValue by one, converts the resulting number to its hexadecimal string representation, and then calls the ToInt16(String, Int32) method. Instead of throwing an exception, the method displays the message, "0x8000 converts to -32768."


// Create a hexadecimal value out of range of the Int16 type.
string value = Convert.ToString((int) short.MaxValue + 1, 16);
// Convert it back to a number.
try
{
   short number = Convert.ToInt16(value, 16);
   Console.WriteLine("0x{0} converts to {1}.", value, number);
}
catch (OverflowException)
{
   Console.WriteLine("Unable to convert '0x{0}' to a 16-bit integer.", value);
}   


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 Short type.
int sourceNumber = (int) short.MaxValue + 1;
bool isNegative = (Math.Sign(sourceNumber) == -1);
string value = Convert.ToString(sourceNumber, 16);
short targetNumber;
try
{
   targetNumber = Convert.ToInt16(value, 16);
   if (! isNegative && ((targetNumber & 0x8000) != 0))
      throw new OverflowException();
   else 
      Console.WriteLine("0x{0} converts to {1}.", value, targetNumber);
}
catch (OverflowException)
{
   Console.WriteLine("Unable to convert '0x{0}' to a 16-bit integer.", value);
} 
// Displays the following to the console:
//    Unable to convert '0x8000' to a 16-bit integer.     


The following example attempts to interpret each element in a string array as a hexadecimal string and to convert it to a 16-bit signed integer.


using System;

public class Example
{
   public static void Main()
   {
      string[] hexStrings = { "8000", "0FFF", "f000", "00A30", "D", "-13", 
                              "9AC61", "GAD" };
      foreach (string hexString in hexStrings)
      {
         try {
            short number = Convert.ToInt16(hexString, 16);
            Console.WriteLine("Converted '{0}' to {1:N0}.", hexString, number);
         }
         catch (FormatException) {
            Console.WriteLine("'{0}' is not in the correct format for a hexadecimal number.", 
                              hexString);
         }
         catch (OverflowException) {
            Console.WriteLine("'{0}' is outside the range of an Int16.", hexString);
         }
         catch (ArgumentException) {
            Console.WriteLine("'{0}' is invalid in base 16.", hexString);
         }
      }                                            
   }
}
// The example displays the following output:
//       Converted '8000' to -32,768.
//       Converted '0FFF' to 4,095.
//       Converted 'f000' to -4,096.
//       Converted '00A30' to 2,608.
//       Converted 'D' to 13.
//       '-13' is invalid in base 16.
//       '9AC61' is outside the range of an Int16.
//       'GAD' is not in the correct format for a hexadecimal number.


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

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