---
metadata:
  - name: generator
    content: Diplodoc Platform v5.50.6
alternate:
  - https://ytsaurus.tech/docs/en/yql/udf/list/string.md
  - https://ytsaurus.tech/docs/ru/yql/udf/list/string.md
---
> **Documentation Index:** Fetch the complete configuration index at https://ytsaurus.tech/docs/en/llms.txt

# String

Functions for ASCII strings:

## List of functions

* `String::Base64Encode(String{Flags:AutoMap}) -> String`

* `String::Base64Decode(String) -> String?`

* `String::Base64StrictDecode(String) -> String?`

* `String::EscapeC(String{Flags:AutoMap}) -> String`

* `String::UnescapeC(String{Flags:AutoMap}) -> String`

* `String::HexEncode(String{Flags:AutoMap}) -> String`

* `String::HexDecode(String) -> String?`

* `String::EncodeHtml(String{Flags:AutoMap}) -> String`

* `String::DecodeHtml(String{Flags:AutoMap}) -> String`

* `String::CgiEscape(String{Flags:AutoMap}) -> String`

* `String::CgiUnescape(String{Flags:AutoMap}) -> String`

* `String::Strip(String{Flags:AutoMap}) -> String`

* `String::Collapse(String{Flags:AutoMap}) -> String`

* `String::CollapseText(String{Flags:AutoMap}, Uint64) -> String`

* `String::AsciiEqualsIgnoreCase(String?, String) -> Bool` Added in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::Contains(String?, String) -> Bool`

* `String::AsciiContainsIgnoreCase(String?, String) -> Bool` Added in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::Find(String{Flags:AutoMap}, String, [Uint64?]) -> Int64`: Returns the first position found or -1. The optional argument is the offset from the beginning of the string.

* `String::ReverseFind(String{Flags:AutoMap}, String, [Uint64?]) -> Int64`: Returns the last position found or -1. The optional argument is the offset from the beginning of the string.

* `String::AsciiStartsWithIgnoreCase(String?, String) -> Bool` Added in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::HasPrefix(String?, String) -> Bool`

* `String::HasPrefixIgnoreCase(String?, String) -> Bool` Removed in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::StartsWith(String?, String) -> Bool`

* `String::StartsWithIgnoreCase(String?, String) -> Bool` Removed in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::AsciiEndsWithIgnoreCase(String?, String) -> Bool` Added in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::HasSuffix(String?, String) -> Bool`

* `String::HasSuffixIgnoreCase(String?, String) -> Bool` Removed in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::EndsWith(String?, String) -> Bool`

* `String::EndsWithIgnoreCase(String?, String) -> Bool` Removed in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

* `String::Substring(String{Flags:AutoMap}, [Uint64?, Uint64?]) -> String`

* `String::AsciiToLower(String{Flags:AutoMap}) -> String`: Changes only Latin characters. For working with other alphabets, see Unicode::ToLower

* `String::AsciiToUpper(String{Flags:AutoMap}) -> String`: Changes only Latin characters. For working with other alphabets, see Unicode::ToUpper

* `String::AsciiToTitle(String{Flags:AutoMap}) -> String`: Changes only Latin characters. For working with other alphabets, see Unicode::ToTitle

* `String::SplitToList( String?, String, [ DelimeterString:Bool?, SkipEmpty:Bool?, Limit:Uint64? ]) -> List<String>`

  The first argument is the source string
  The second argument is a delimiter
  The third argument includes the following parameters:

  - DelimeterString:Bool? — treating a delimiter as a string (true, by default) or a set of characters "any of" (false)
  - SkipEmpty:Bool? — whether to skip empty strings in the result, is false by default
  - Limit:Uint64? — Limits the number of fetched components (unlimited by default); if the limit is exceeded, the raw suffix of the source string is returned in the last item

* `String::JoinFromList(List<String>{Flags:AutoMap}, String) -> String`

* `String::ToByteList(List<String>{Flags:AutoMap}) -> List<Byte>`

* `String::FromByteList(List<Uint8>) -> String`

* `String::ReplaceAll(String{Flags:AutoMap}, String, String) -> String`: Arguments: input, find, replacement

* `String::ReplaceFirst(String{Flags:AutoMap}, String, String) -> String`: Arguments: input, find, replacement

* `String::ReplaceLast(String{Flags:AutoMap}, String, String) -> String`: Arguments: input, find, replacement

* `String::RemoveAll(String{Flags:AutoMap}, String) -> String`: The second argument is interpreted as an unordered set of characters to delete

* `String::RemoveFirst(String{Flags:AutoMap}, String) -> String`: An unordered set of characters in the second argument, only the first encountered character from set is deleted

* `String::RemoveLast(String{Flags:AutoMap}, String) -> String`: An unordered set of characters in the second argument, only the last encountered character from the set is deleted

* `String::ReverseBytes(String{Flags:AutoMap}) -> String` - Added in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)
  Reverses a string, treating it as a byte sequence.

* `String::ReverseBits(String{Flags:AutoMap}) -> String` - Added in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)
  Reverses a string, treating it as a bit sequence.

* `String::IsAscii(String{Flags:AutoMap}) -> Bool`

* `String::IsAsciiSpace(String{Flags:AutoMap}) -> Bool`

* `String::IsAsciiUpper(String{Flags:AutoMap}) -> Bool`

* `String::IsAsciiLower(String{Flags:AutoMap}) -> Bool`

* `String::IsAsciiAlpha(String{Flags:AutoMap}) -> Bool`

* `String::IsAsciiAlnum(String{Flags:AutoMap}) -> Bool`

* `String::IsAsciiHex(String{Flags:AutoMap}) -> Bool`

* `String::LevensteinDistance(String{Flags:AutoMap}, String{Flags:AutoMap}) -> Uint64`

* `String::LeftPad(String{Flags:AutoMap}, Uint64, [String?]) -> String`

* `String::RightPad(String{Flags:AutoMap}, Uint64) -> String`

* `String::Hex(Uint64{Flags:AutoMap}) -> String`

* `String::SHex(Int64{Flags:AutoMap}) -> String`

* `String::Bin(Uint64{Flags:AutoMap}) -> String`

* `String::SBin(Int64{Flags:AutoMap}) -> String`

* `String::HexText(String{Flags:AutoMap}) -> String`

* `String::BinText(String{Flags:AutoMap}) -> String`

* `String::HumanReadableDuration(Uint64{Flags:AutoMap}) -> String`

* `String::HumanReadableQuantity(Uint64{Flags:AutoMap}) -> String`

* `String::HumanReadableBytes(Uint64{Flags:AutoMap}) -> String`

* `String::Prec(Double{Flags:AutoMap}, Uint64) -> String`

* `String::Reverse(String?) -> String?` Removed in the version [2025.02](https://ytsaurus.tech/docs/en/yql/changelog/2025.02.md#string-module)

{% note alert %}

The functions from the String library don't support Cyrillic and can only work with ASCII characters. To work with UTF-8 encoded strings, use functions from [Unicode](https://ytsaurus.tech/docs/en/yql/udf/list/unicode.md).

{% endnote %}

## Examples

```yql
SELECT String::Base64Encode("YQL"); -- "WVFM"
SELECT String::Strip("YQL ");       -- "YQL"
SELECT String::SplitToList("1,2,3,4,5,6,7", ",", 3 as Limit); -- ["1", "2", "3", "4,5,6,7"]
```