System Namespace Convert Class
Converts the specified String representation of a value consisting of base 64 digits to an equivalent array of 8-bit unsigned integers.
[ VB ]
Public Shared Function FromBase64String ( _
ByVal s As String _
) As Byte ( )
[ C# ]
public static byte[ ] FromBase64String (
string s
);
[ C++ ]
public: static unsigned char FromBase64String (
String* s
) __gc [ ];
[ JScript ]
public static function FromBase64String (
s : String
) : Byte[ ];
- s
- A String.
An array of 8-bit unsigned integers equivalent to s.
| Exception Type |
Condition |
| ArgumentNullException |
s is a null reference ( Nothing in Visual Basic ). |
| FormatException |
The length of s is less than 4.
-or-
The length of s is not an even multiple of 4.
|
s is composed of base 64 digits. The base 64 digits in ascending order from zero are the uppercase characters 'A' to 'Z', lowercase characters 'a' to 'z', numerals '0' to '9', and the symbols '+' and '/'. The valueless character, '=', is used for trailing padding.
The following sample demonstrates using the FromBase64String method.
[ VB ]
Public Sub DecodeWithString ( )
Dim inFile As System.IO.StreamReader
Dim base64String As String
Try
Dim base64CharArray ( ) As Char
inFile = New System.IO.StreamReader ( inputFileName, _
System.Text.Encoding.ASCII )
base64CharArray = New Char ( inFile.BaseStream.Length ) {}
inFile.Read ( base64CharArray, 0, inFile.BaseStream.Length )
base64String = New String ( base64CharArray, _
0, _
base64CharArray.Length - 1 )
Catch exp As System.Exception
' Error creating stream or reading from it.
System.Response.WriteLine ( "{0}", exp.Message )
Return
End Try
' Convert the Base64 UUEncoded input into binary output.
Dim binaryData ( ) As Byte
Try
binaryData = System.Convert.FromBase64String ( base64String )
Catch exp As System.ArgumentNullException
System.Response.WriteLine ( "Base 64 string is null." )
Return
Catch exp As System.FormatException
System.Response.WriteLine ( "Base 64 length is not 4 or is " + _
"not an even multiple of 4." )
Return
End Try
'Write out the decoded data.
Dim outFile As System.IO.FileStream
Try
outFile = New System.IO.FileStream ( outputFileName, _
System.IO.FileMode.Create, _
System.IO.FileAccess.Write )
outFile.Write ( binaryData, 0, binaryData.Length - 1 )
outFile.Close ( )
Catch exp As System.Exception
' Error creating stream or writing to it.
System.Response.WriteLine ( "{0}", exp.Message )
End Try
End Sub
[ C# ]
public void DecodeWithString ( ) {
System.IO.StreamReader inFile;
string base64String;
try {
char [ ] base64CharArray;
inFile = new System.IO.StreamReader ( inputFileName,
System.Text.Encoding.ASCII );
base64CharArray = new char [ inFile.BaseStream.Length ];
inFile.Read ( base64CharArray, 0, ( int ) inFile.BaseStream.Length );
base64String = new string ( base64CharArray );
}
catch ( System.Exception exp ) {
// Error creating stream or reading from it.
System.Response.WriteLine ( "{0}", exp.Message );
return;
}
// Convert the Base64 UUEncoded input into binary output.
byte [ ] binaryData;
try {
binaryData =
System.Convert.FromBase64String ( base64String );
}
catch ( System.ArgumentNullException ) {
System.Response.WriteLine ( "Base 64 string is null." );
return;
}
catch ( System.FormatException ) {
System.Response.WriteLine ( "Base 64 string length is not " +
"4 or is not an even multiple of 4." );
return;
}
// Write out the decoded data.
System.IO.FileStream outFile;
try {
outFile = new System.IO.FileStream ( outputFileName,
System.IO.FileMode.Create,
System.IO.FileAccess.Write );
outFile.Write ( binaryData, 0, binaryData.Length );
outFile.Close ( );
}
catch ( System.Exception exp ) {
// Error creating stream or writing to it.
System.Response.WriteLine ( "{0}", exp.Message );
}
}
Convert Members
