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Convert Class

Converts a base data type to another base data type.

For a list of all members of this type, see Convert Members.

System.Object
   System.Convert

[Visual Basic]
NotInheritable Public Class Convert
[C#]
public sealed class Convert
[C++]
public __gc __sealed class Convert
[JScript]
public class Convert

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

This class returns a type whose value is equivalent to the value of a specified type. The supported base types are Boolean, Char, SByte, Byte, Int16, Int32, Int64, UInt16, UInt32, UInt64, Single, Double, Decimal, DateTime and String.

A conversion method exists to convert every base type to every other base type. However, the actual conversion operation performed falls into three categories:

  • A conversion from a type to itself simply returns that type. No conversion is actually performed.
  • A conversion which cannot yield a meaningful result throws InvalidCastException. No conversion is actually performed. An exception is thrown for conversions from Char to Boolean, Single, Double, Decimal or DateTime, and from those types to Char. An exception is thrown for conversions from DateTime to any type except String, and from any type, except String, to DateTime.
  • Any base type, other than those described above, can be converted to and from any other base type.

An exception will not be thrown if the conversion of a numeric type results in a loss of precision (that is, the loss of some least significant digits). However, an exception will be thrown if the result is larger than can be represented by the particular conversion method's return value type.

For example, when a Double is converted to a Single, a loss of precision might occur but no exception is thrown. However, if the magnitude of the Double is too large to be represented by a Single, an overflow exception is thrown.

A set of methods support converting an array of bytes to and from a String or array of Unicode characters consisting of base 64 digit characters. Data expressed as base 64 digits can be easily conveyed over data channels that can only transmit 7-bit characters.

Many of the methods in this class convert a source type to a target type by invoking the corresponding IConvertible explicit interface implementation method on the source object. If such a method does not exist, an InvalidCastException is thrown.

Some of the methods in this class take a parameter object that implements the IFormatProvider interface. This parameter can supply culture-specific formatting information to assist the conversion process. The base value types ignore this parameter, but any user-defined type that implements IConvertible can honor it.

For more information about the base value types, see the appropriate topic listed in the See Also section.

Example

[Visual Basic, C#, C++] The following sample demonstrates some of the conversion methods in this class, including ToInt32, ToBoolean, and ToString.

[Visual Basic] 
Dim dNumber As Double
dNumber = 23.15

Try
   ' Returns 23
   Dim iNumber As Integer
   iNumber = System.Convert.ToInt32(dNumber)
Catch exp As System.OverflowException
   System.Console.WriteLine("Overflow in double to int conversion.")
End Try

' Returns True
Dim bNumber As Boolean
bNumber = System.Convert.ToBoolean(dNumber)

' Returns "23.15"
Dim strNumber As String
strNumber = System.Convert.ToString(dNumber)

Try
   ' Returns '2'
   Dim chrNumber As Char
   chrNumber = System.Convert.ToChar(strNumber.Chars(1))
Catch exp As System.ArgumentNullException
   System.Console.WriteLine("String is null.")
Catch exp As System.FormatException
   System.Console.WriteLine("String length is greater than 1.")
End Try

' System.Console.ReadLine() returns a string and it
' must be converted.
Dim newInteger As Integer
newInteger = 0
Try
   System.Console.WriteLine("Enter an integer:")
   newInteger = System.Convert.ToInt32(System.Console.ReadLine())
Catch exp As System.ArgumentNullException
   System.Console.WriteLine("String is null.")
Catch exp As System.FormatException
   System.Console.WriteLine("String does not consist of an " + _
       "optional sign followed by a series of digits.")
Catch exp As System.OverflowException
   System.Console.WriteLine("Overflow in string to int conversion.")
End Try

System.Console.WriteLine("Your integer as a double is {0}", _
                         System.Convert.ToDouble(newInteger))

[C#] 
double dNumber = 23.15;

try {
    // Returns 23
    int    iNumber = System.Convert.ToInt32(dNumber);
}
catch (System.OverflowException) {
    System.Console.WriteLine(
                "Overflow in double to int conversion.");
}
// Returns True
bool   bNumber = System.Convert.ToBoolean(dNumber);

// Returns "23.15"
string strNumber = System.Convert.ToString(dNumber);

try {
    // Returns '2'
    char chrNumber = System.Convert.ToChar(strNumber[0]);
} 
catch (System.ArgumentNullException) {
    System.Console.WriteLine("String is null");
}
catch (System.FormatException) {
    System.Console.WriteLine("String length is greater than 1.");
}

// System.Console.ReadLine() returns a string and it
// must be converted.
int newInteger = 0;
try {
    System.Console.WriteLine("Enter an integer:");
    newInteger = System.Convert.ToInt32(
                        System.Console.ReadLine());
}
catch (System.ArgumentNullException) {
    System.Console.WriteLine("String is null.");
}
catch (System.FormatException) {
    System.Console.WriteLine("String does not consist of an " +
                    "optional sign followed by a series of digits.");
} 
catch (System.OverflowException) {
    System.Console.WriteLine(
    "Overflow in string to int conversion.");
}

System.Console.WriteLine("Your integer as a double is {0}",
                         System.Convert.ToDouble(newInteger));

[C++] 
Double dNumber = 23.15;

try {
    // Returns 23
    Int32 iNumber = Convert::ToInt32(dNumber);
}
catch (OverflowException*) {
    Console::WriteLine("Overflow in Double to Int32 conversion");
}

// Returns True
Boolean bNumber = Convert::ToBoolean(dNumber);
        
// Returns "23.15"
String* strNumber = Convert::ToString(dNumber);

try {
    // Returns '2'
    Char chrNumber = Convert::ToChar(strNumber->Substring(0,1));
} 
catch (ArgumentNullException*) {
    Console::WriteLine("String is null");
}
catch (FormatException*) {
    Console::WriteLine("String length is greater than 1");
}

// Console.ReadLine() returns a string and it
// must be converted.
Int32 newInteger = 0;
try {
    Console::WriteLine("Enter an integer:");
    newInteger = Convert::ToInt32("10001");
}
catch (ArgumentNullException*) {
    Console::WriteLine("String is null");
}
catch (FormatException*) {
    Console::WriteLine("String does not consist of an optional sign followed by a series of digits");
} 
catch (OverflowException*) {
    Console::WriteLine("Overflow in string to Int32 conversion");
}

Console::WriteLine("Your integer as a Double is {0}", __box(Convert::ToDouble(newInteger)));

[Visual Basic] 
' Sample for the Convert class summary.
Imports System

Class Sample
   Public Shared Sub Main()
      Dim nl As String = Environment.NewLine
      Dim str As String = "{0}Return the Int64 equivalent of the following base types:{0}"
      Dim xBool As Boolean = False
      Dim xShort As Short = 1
      Dim xInt As Integer = 2
      Dim xLong As Long = 3
      Dim xSingle As Single = 4F
      Dim xDouble As Double = 5.0
      Dim xDecimal As Decimal = 6D
      Dim xString As String = "7"
      Dim xChar As Char = "8"c ' '8' = hexadecimal 38 = decimal 56
      Dim xByte As Byte = 9
      
      '  The following types are not CLS-compliant.
      ' Dim xUshort As System.UInt16 = 120
      ' Dim xUint As System.UInt32 = 121
      ' Dim xUlong As System.UInt64 = 122
      ' Dim xSbyte As System.SByte = 123
      
      '  The following type cannot be converted to an Int64.
      '  Dim xDateTime As System.DateTime = DateTime.Now

      Console.WriteLine(str, nl)
      Console.WriteLine("Boolean:  {0}", Convert.ToInt64(xBool))
      Console.WriteLine("Int16:    {0}", Convert.ToInt64(xShort))
      Console.WriteLine("Int32:    {0}", Convert.ToInt64(xInt))
      Console.WriteLine("Int64:    {0}", Convert.ToInt64(xLong))
      Console.WriteLine("Single:   {0}", Convert.ToInt64(xSingle))
      Console.WriteLine("Double:   {0}", Convert.ToInt64(xDouble))
      Console.WriteLine("Decimal:  {0}", Convert.ToInt64(xDecimal))
      Console.WriteLine("String:   {0}", Convert.ToInt64(xString))
      Console.WriteLine("Char:     {0}", Convert.ToInt64(xChar))
      Console.WriteLine("Byte:     {0}", Convert.ToInt64(xByte))
      Console.WriteLine("DateTime: There is no example of this conversion because")
      Console.WriteLine("          a DateTime cannot be converted to an Int64.")
      '
      Console.Write("{0}The following types are not supported: ", nl)
      Console.WriteLine("UInt16, UInt32, UInt64, and SByte")
   End Sub 'Main
End Class 'Sample
'
'This example produces the following results:
'
'Return the Int64 equivalent of the following base types:
'
'Boolean:  0
'Int16:    1
'Int32:    2
'Int64:    3
'Single:   4
'Double:   5
'Decimal:  6
'String:   7
'Char:     56
'Byte:     9
'DateTime: There is no example of this conversion because
'          a DateTime cannot be converted to an Int64.
'
'The following types are not supported: UInt16, UInt32, UInt64, and SByte
'

[C#] 
// Sample for the Convert class summary.
using System;

class Sample 
{
    public static void Main() 
    {
    string nl = Environment.NewLine;
    string str = "{0}Return the Int64 equivalent of the following base types:{0}";
    bool    xBool = false;
    short   xShort = 1;
    int     xInt   = 2;
    long    xLong  = 3;
    float   xSingle = 4.0f;
    double  xDouble = 5.0;
    decimal xDecimal = 6.0m;
    string  xString = "7";
    char    xChar   = '8'; // '8' = hexadecimal 38 = decimal 56
    byte    xByte  =  9;

//  The following types are not CLS-compliant.
    ushort  xUshort = 120;   
    uint    xUint =   121;
    ulong   xUlong =  122;
    sbyte   xSbyte  = 123;

//  The following type cannot be converted to an Int64.
//  DateTime xDateTime = DateTime.Now;

    Console.WriteLine(str, nl);
    Console.WriteLine("Boolean:  {0}", Convert.ToInt64(xBool));
    Console.WriteLine("Int16:    {0}", Convert.ToInt64(xShort));
    Console.WriteLine("Int32:    {0}", Convert.ToInt64(xInt));
    Console.WriteLine("Int64:    {0}", Convert.ToInt64(xLong));
    Console.WriteLine("Single:   {0}", Convert.ToInt64(xSingle));
    Console.WriteLine("Double:   {0}", Convert.ToInt64(xDouble));
    Console.WriteLine("Decimal:  {0}", Convert.ToInt64(xDecimal));
    Console.WriteLine("String:   {0}", Convert.ToInt64(xString));
    Console.WriteLine("Char:     {0}", Convert.ToInt64(xChar));
    Console.WriteLine("Byte:     {0}", Convert.ToInt64(xByte));
    Console.WriteLine("DateTime: There is no example of this conversion because");
    Console.WriteLine("          a DateTime cannot be converted to an Int64.");
//
    Console.WriteLine("{0}The following types are not CLS-compliant.{0}", nl);
    Console.WriteLine("UInt16:   {0}", Convert.ToInt64(xUshort));
    Console.WriteLine("UInt32:   {0}", Convert.ToInt64(xUint));
    Console.WriteLine("UInt64:   {0}", Convert.ToInt64(xUlong));
    Console.WriteLine("SByte:    {0}", Convert.ToInt64(xSbyte));
    }
}
/*
This example produces the following results:

Return the Int64 equivalent of the following base types:

Boolean:  0
Int16:    1
Int32:    2
Int64:    3
Single:   4
Double:   5
Decimal:  6
String:   7
Char:     56
Byte:     9
DateTime: There is no example of this conversion because
          a DateTime cannot be converted to an Int64.

The following types are not CLS-compliant.

UInt16:   120
UInt32:   121
UInt64:   122
SByte:    123
*/

[C++] 
// Sample for the Convert class summary.
#using <mscorlib.dll>

using namespace System;


int main() {
   String* nl = Environment::NewLine;
   String* str = S" {0}Return the Int64 equivalent of the following base types: {0}";
   bool    xBool = false;
   short   xShort = 1;
   int     xInt   = 2;
   long    xLong  = 3;
   float   xSingle = 4.0f;
   double  xDouble = 5.0;
   Decimal xDecimal = 6.0;
   String*  xString = S"7";
   char    xChar   = '8'; // '8' = hexadecimal 38 = decimal 56
   Byte    xByte  =  9;

   //  The following types are not CLS-compliant.
   UInt16  xUshort = 120;
   UInt32    xUint =   121;
   UInt64   xUlong =  122;
   SByte   xSbyte  = 123;

   //  The following type cannot be converted to an Int64.
   //  DateTime xDateTime = DateTime::Now;

   Console::WriteLine(str, nl);
   Console::WriteLine(S"Boolean: {0}", __box(Convert::ToInt64(xBool)));
   Console::WriteLine(S"Int16: {0}", __box(Convert::ToInt64(xShort)));
   Console::WriteLine(S"Int32: {0}", __box(Convert::ToInt64(xInt)));
   Console::WriteLine(S"Int64: {0}", __box(Convert::ToInt64(xLong)));
   Console::WriteLine(S"Single: {0}", __box(Convert::ToInt64(xSingle)));
   Console::WriteLine(S"Double: {0}", __box(Convert::ToInt64(xDouble)));
   Console::WriteLine(S"Decimal: {0}", __box(Convert::ToInt64(xDecimal)));
   Console::WriteLine(S"String: {0}", __box(Convert::ToInt64(xString)));
   Console::WriteLine(S"Char: {0}", __box(Convert::ToInt64(xChar)));
   Console::WriteLine(S"Byte: {0}", __box(Convert::ToInt64(xByte)));
   Console::WriteLine(S"DateTime: There is no example of this conversion because");
   Console::WriteLine(S"          a DateTime cannot be converted to an Int64.");
   //
   Console::WriteLine(S" {0}The following types are not CLS-compliant. {0}", nl);
   Console::WriteLine(S"UInt16: {0}", __box(Convert::ToInt64(xUshort)));
   Console::WriteLine(S"UInt32: {0}", __box(Convert::ToInt64(xUint)));
   Console::WriteLine(S"UInt64: {0}", __box(Convert::ToInt64(xUlong)));
   Console::WriteLine(S"SByte: {0}", __box(Convert::ToInt64(xSbyte)));
}
/*
This example produces the following results:

Return the Int64 equivalent of the following base types:

Boolean:  0
Int16:    1
Int32:    2
Int64:    3
Single:   4
Double:   5
Decimal:  6
String:   7
Char:     56
Byte:     9
DateTime: There is no example of this conversion because
a DateTime cannot be converted to an Int64.

The following types are not CLS-compliant.

UInt16:   120
UInt32:   121
UInt64:   122
SByte:    123
*/

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

Convert Members | System Namespace | Object | SByte | Int16 | Int32 | Int64 | Byte | UInt16 | UInt32 | UInt64 | Single | Double | Decimal | Boolean | Char | String

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