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* Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype
28 lines
1.9 KiB
Markdown
28 lines
1.9 KiB
Markdown
# Encoding functions
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## hex
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Accepts arguments of types: `String`, `unsigned integer`, `Date`, or `DateTime`. Returns a string containing the argument's hexadecimal representation. Uses uppercase letters `A-F`. Does not use `0x` prefixes or `h` suffixes. For strings, all bytes are simply encoded as two hexadecimal numbers. Numbers are converted to big endian ("human readable") format. For numbers, older zeros are trimmed, but only by entire bytes. For example, `hex (1) = '01'`. `Date` is encoded as the number of days since the beginning of the Unix epoch. `DateTime` is encoded as the number of seconds since the beginning of the Unix epoch.
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## unhex(str)
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Accepts a string containing any number of hexadecimal digits, and returns a string containing the corresponding bytes. Supports both uppercase and lowercase letters A-F. The number of hexadecimal digits does not have to be even. If it is odd, the last digit is interpreted as the younger half of the 00-0F byte. If the argument string contains anything other than hexadecimal digits, some implementation-defined result is returned (an exception isn't thrown).
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If you want to convert the result to a number, you can use the 'reverse' and 'reinterpretAsType' functions.
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## UUIDStringToNum(str)
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Accepts a string containing 36 characters in the format `123e4567-e89b-12d3-a456-426655440000`, and returns it as a set of bytes in a FixedString(16).
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## UUIDNumToString(str)
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Accepts a FixedString(16) value. Returns a string containing 36 characters in text format.
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## bitmaskToList(num)
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Accepts an integer. Returns a string containing the list of powers of two that total the source number when summed. They are comma-separated without spaces in text format, in ascending order.
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## bitmaskToArray(num)
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Accepts an integer. Returns an array of UInt64 numbers containing the list of powers of two that total the source number when summed. Numbers in the array are in ascending order.
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