Surrogate Pairs

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This page only gives you an example of how you can encode characters in UTF-16 whose Unicode values are higher than 0xFFFF.  Read RFC 2781 for first-hand information.

1. Take the Unicode value of the character and subtract 0x10000 from it.
   • You can find the Unicode value of a Chinese ideograph in the Unihan Database.
   • You can find the Unicode value of any character in the Unicode Code Charts.
2. Convert the remainder from hexadecimal to binary form and extend the binary number to 20 digits with initial zeros if necessary.
3. Fill in the empty slots of the following template with the twenty digits:

   110110xxxxxxxxxx 110111xxxxxxxxxx

Example

1. Say you want to encode

   

   whose Unicode value is 2A6D6.  0x10000 subtracted from 0x2A6D6 gives 0x1A6D6.

2. Convert 0x1A6D6 to a 20-digit binary number to get

   0001101001 1011010110

3. Fill in the empty slots of the following template

   110110xxxxxxxxxx 110111xxxxxxxxxx

   with the twenty digits:

   1101100001101001 1101111011010110

   and you will get this surrogate pair: 0xD869 0xDED6.

Source of Information

Paul Hoffman & François Yergeau. 2000. UTF-16, an encoding of  ISO 10646. RFC 2781.

• Visit the Internet FAQ Consortium's RFC Archive.