Convert.ToBase64String Method (Byte[], Base64FormattingOptions)


Converts an array of 8-bit unsigned integers to its equivalent string representation that is encoded with base-64 digits. A parameter specifies whether to insert line breaks in the return value.

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

static member ToBase64String : 
        inArray:byte[] *
        options:Base64FormattingOptions -> string


Type: System.Byte[]

An array of 8-bit unsigned integers.

Type: System.Base64FormattingOptions

InsertLineBreaks to insert a line break every 76 characters, or None to not insert line breaks.

Return Value

Type: System.String

The string representation in base 64 of the elements in inArray.

Exception Condition

inArray is null.


options is not a valid Base64FormattingOptions value.

The elements of the inArray parameter are taken as a numeric value and converted to a string representation in base 64.

The base-64 digits in ascending order from zero are the uppercase characters "A" to "Z", the lowercase characters "a" to "z", the numerals "0" to "9", and the symbols "+" and "/". The valueless character "=" is used for trailing padding.


The ToBase64String method is designed to process a single byte array that contains all the data to be encoded. To encode data from a stream, use the System.Security.Cryptography.ToBase64Transform class.

If the options parameter is set to InsertLineBreaks and the output of the conversion is longer than 76 characters, a line break is inserted every 76 characters. A line break is defined as a carriage return character (U+000D) followed by a line feed character (U+000A). Because line breaks are considered whitespace characters in a base-64 encoding, they are ignored when converting a base-64 encoded string back to a byte array. The line breaks are simply convenient when displaying the encoded string to a control or a device such as a console window. For more information, see RFC 2045, "Multipurpose Internet Mail Extensions", at

The following example calls the Convert.ToBase64String(Byte[], Base64FormattingOptions) with a Base64FormattingOptions.InsertLineBreaks argument to insert line breaks in the string that is produced by encoding a 100-element byte array.

No code example is currently available or this language may not be supported.

As the output from the example shows, the Convert.FromBase64String succeeds in restoring the original byte array; the line break characters are ignored during the conversion.

.NET Framework
Available since 2.0
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