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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 containing a number.
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 equivalent to the number in value.
-or-
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-

The return value is less than Int16.MinValue or larger 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. Rather than 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);
   outputBlock.Text += String.Format("0x{0} converts to {1}.", value, number) + "\n";
}
catch (OverflowException)
{
   outputBlock.Text += String.Format("Unable to convert '0x{0}' to a 16-bit integer.", value) + "\n";
}


When performing binary operations or numeric conversions, it is always the responsibility of the developer to verify that a method uses 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. Then, throw an exception if the conversion back to an integer yields a negative value when the original value was positive.


// 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
      outputBlock.Text += String.Format("0x{0} converts to {1}.", value, targetNumber) + "\n";
}
catch (OverflowException)
{
   outputBlock.Text += String.Format("Unable to convert '0x{0}' to a 16-bit integer.", value) + "\n";
}
// Displays the following:
//    Unable to convert '0x8000' to a 16-bit integer.     


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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