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‎docs/compute-engine/97-reference-strings.md‎

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@@ -3,12 +3,211 @@ title: Strings
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slug:/compute-engine/reference/strings/
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---
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A string is a sequence of characters such as`"Hello, World!"` or`"42"`.
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A string is a sequence of characters such as <span style={{fontSize: "1.2rem"}}>`"Hello, 🌍!"`</span> or <span style={{fontSize: "1.2rem"}}>`"Simplify(👨‍🚀 + ⚡️) → 👨‍🎤"`.</span>
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In the Compute Engine, strings are composed of encoding-independent Unicode
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characters and provide access to those characters through a variety of Unicode
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representations.
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In the Compute Engine, strings are**not treated as collections**. This is
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because the concept of a "character" is inherently ambiguous: a single
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user-perceived character (a**grapheme cluster**) may consist of multiple
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Unicode scalars, and those scalars may in turn be represented differently
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in various encodings. To avoid confusion and ensure consistent behavior,
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strings must be explicitly converted to a sequence of**grapheme clusters** or
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**Unicode scalars** when individual elements need to be accessed.
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<navclassName="hidden">
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###String
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</nav>
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<FunctionDefinitionname="String">
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<Signaturename="String"returns="string">any*</Signature>
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A string created by joining its arguments. The arguments are converted to their default string representation.
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```json example
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["String","Hello",",","🌍","!"]
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// ➔ "Hello, 🌍!"
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["String",42," is the answer"]
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// ➔ "42 is the answer"
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```
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</FunctionDefinition>
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<navclassName="hidden">
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###StringFrom
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</nav>
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<FunctionDefinitionname="StringFrom">
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<Signaturename="StringFrom"returns="string">any,_format_:string?</Signature>
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Convert the argument to a string, using the specified_format_.
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|_format_| Description|
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| :---| :---|
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|`utf-8`| The argument is a list of UTF-8 code points|
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|`utf-16`| The argument is a list of UTF-16 code points|
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|`unicode-scalars`| The argument is a list of Unicode scalars (same as UTF-32)|
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For example:
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```json example
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["StringFrom", [240,159,148,159],"utf-8"]
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// ➔ "Hello"
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["StringFrom", [55357,56607],"utf-16"]
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// ➔ "\u0048\u0065\u006c\u006c\u006f"
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["StringFrom", [128287],"unicode-scalars"]
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// ➔ "🔟"
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["StringFrom", [127467,127479],"unicode-scalars"]
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// ➔ "🇫🇷"
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```
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</FunctionDefinition>
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<navclassName="hidden">
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###Utf8
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</nav>
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<FunctionDefinitionname="Utf8">
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<Signaturename="Utf8"returns="list<integer>">string</Signature>
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Return a list of UTF-8 code points for the given_string_.
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**Note:** The values returned are UTF-8 bytes, not Unicode scalar values.
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```json example
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["Utf8","Hello"]
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// ➔ [72, 101, 108, 108, 111]
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["Utf8","👩‍🎓"]
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// ➔ [240, 159, 145, 169, 226, 128, 141, 240, 159, 142, 147]
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```
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</FunctionDefinition>
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<navclassName="hidden">
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###Utf16
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</nav>
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<FunctionDefinitionname="Utf16">
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<Signaturename="Utf16"returns="list<integer>">string</Signature>
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Return a list of utf-16 code points for the given_string_.
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**Note:** The values returned are UTF-16 code units, not Unicode scalar values.
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```json example
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["Utf16","Hello"]
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// ➔ [72, 101, 108, 108, 111]
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["Utf16","👩‍🎓"]
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// ➔ [55357, 56489, 8205, 55356, 57235]
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```
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</FunctionDefinition>
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<navclassName="hidden">
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###UnicodeScalars
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</nav>
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<FunctionDefinitionname="UnicodeScalars">
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<Signaturename="UnicodeScalars"returns="list<integer>">string</Signature>
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A**Unicode scalar** is any valid Unicode code point, represented as a number
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between`U+0000` and`U+10FFFF`, excluding the surrogate range
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(`U+D800` to`U+DFFF`). In other words, Unicode scalars correspond exactly to UTF-32 code units.
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This function returns the sequence of Unicode scalars (code points) that make
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up the string. Note that some characters perceived as a single visual unit
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(grapheme clusters) may consist of multiple scalars. For example, the emoji
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<span style={{fontSize: "1.2em"}}>👩‍🚀</span> is a single grapheme but is composed of several scalars.
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```json example
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["UnicodeScalars","Hello"]
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// ➔ [72, 101, 108, 108, 111]
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["UnicodeScalars","👩‍🎓"]
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// ➔ [128105, 8205, 127891]
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```
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</FunctionDefinition>
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<navclassName="hidden">
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###GraphemeClusters
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</nav>
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<FunctionDefinitionname="GraphemeClusters">
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<Signaturename="GraphemeClusters"returns="list<string>">string</Signature>
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A**grapheme cluster** is the smallest unit of text that a reader perceives
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as a single character. It may consist of one or more**Unicode scalars**
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(code points).
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For example, the character**é** can be a single scalar (`U+00E9`) or a
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sequence of scalars (**e**`U+0065` +**combining acute**`U+0301`),
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but both form a single grapheme cluster.
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Here,**NFC** (Normalization Form C) refers to the precomposed form of characters, while**NFD** (Normalization Form D) refers to the decomposed form where combining marks are used.
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Similarly, complex emojis (<span style={{fontSize: "1.2rem"}}>👩‍🚀</span>, <span style={{fontSize: "1.2rem"}}>🇫🇷</span>)
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are grapheme clusters composed of multiple scalars.
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The exact definition of grapheme clusters is determined by the Unicode Standard
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([UAX#29](https://unicode.org/reports/tr29/)) and may evolve over time as new
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characters, scripts, or emoji sequences are introduced. In contrast, Unicode
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scalars and their UTF-8, UTF-16, or UTF-32 encodings are fixed and stable across Unicode versions.
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The table below illustrates the difference between grapheme clusters and Unicode scalars:
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| String| Grapheme Clusters| Unicode Scalars (Code Points)|
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|:-------------|:--------------------|:------------------------------------|
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| <span style={{fontSize: "1.3rem"}}>`é`</span> (NFC)| <span style={{fontSize: "1.3rem"}}>`["é"]`</span>|`[233]`|
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| <span style={{fontSize: "1.3rem"}}>`é`</span> (NFD)| <span style={{fontSize: "1.3rem"}}>`["é"]`</span>|`[101, 769]`|
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| <span style={{fontSize: "1.3rem"}}>`👩‍🎓`</span>| <span style={{fontSize: "1.3rem"}}>`["👩‍🎓"]`</span>|`[128105, 8205, 127891]`|
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In contrast, a Unicode scalar is a single code point in the Unicode standard,
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corresponding to a UTF-32 value. Grapheme clusters are built from one or more scalars.
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This function splits a string into grapheme clusters, not scalars.
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```json example
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["GraphemeClusters","Hello"]
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// ➔ ["H", "e", "l", "l", "o"]
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["GraphemeClusters","👩‍🎓"]
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// ➔ ["👩‍🎓"]
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["UnicodeScalars","👩‍🎓"]
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// ➔ [128105, 8205, 127891]
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```
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For more details on how grapheme cluster boundaries are determined,
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see[Unicode® Standard Annex#29](https://unicode.org/reports/tr29/).
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</FunctionDefinition>
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<navclassName="hidden">
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###BaseForm
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</nav>
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<FunctionDefinitionname="BaseForm">
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<Signaturename="BaseForm"returns="string">_value:integer_</Signature>
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<Signaturename="BaseForm"returns="string">_value_:integer</Signature>
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<Signaturename="BaseForm"returns="string">_value_:integer,_base_</Signature>
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<Signaturename="BaseForm"returns="string">_value_:integer,_base_:integer</Signature>
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Format an_integer_ in a specific_base_, such as hexadecimal or binary.
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