String functions for Bicep

Artikkeli
07/11/2024

This article describes the Bicep functions for working with strings.

base64

base64(inputString)

Returns the base64 representation of the input string.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
inputString	Yes	string	The value to return as a base64 representation.

Return value

A string containing the base64 representation.

Examples

The following example shows how to use the base64 function.

param stringData string = 'one, two, three'
param jsonFormattedData string = '{\'one\': \'a\', \'two\': \'b\'}'

var base64String = base64(stringData)
var base64Object = base64(jsonFormattedData)

output base64Output string = base64String
output toStringOutput string = base64ToString(base64String)
output toJsonOutput object = base64ToJson(base64Object)

The output from the preceding example with the default values is:

Name	Type	Value
base64Output	String	b25lLCB0d28sIHRocmVl
toStringOutput	String	one, two, three
toJsonOutput	Object	{"one": "a", "two": "b"}

base64ToJson

base64ToJson(base64Value)

Converts a base64 representation to a JSON object.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
base64Value	Yes	string	The base64 representation to convert to a JSON object.

Return value

A JSON object.

Examples

The following example uses the base64ToJson function to convert a base64 value:

param stringData string = 'one, two, three'
param jsonFormattedData string = '{\'one\': \'a\', \'two\': \'b\'}'

var base64String = base64(stringData)
var base64Object = base64(jsonFormattedData)

output base64Output string = base64String
output toStringOutput string = base64ToString(base64String)
output toJsonOutput object = base64ToJson(base64Object)

The output from the preceding example with the default values is:

Name	Type	Value
base64Output	String	b25lLCB0d28sIHRocmVl
toStringOutput	String	one, two, three
toJsonOutput	Object	{"one": "a", "two": "b"}

base64ToString

base64ToString(base64Value)

Converts a base64 representation to a string.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
base64Value	Yes	string	The base64 representation to convert to a string.

Return value

A string of the converted base64 value.

Examples

The following example uses the base64ToString function to convert a base64 value:

param stringData string = 'one, two, three'
param jsonFormattedData string = '{\'one\': \'a\', \'two\': \'b\'}'

var base64String = base64(stringData)
var base64Object = base64(jsonFormattedData)

output base64Output string = base64String
output toStringOutput string = base64ToString(base64String)
output toJsonOutput object = base64ToJson(base64Object)

The output from the preceding example with the default values is:

Name	Type	Value
base64Output	String	b25lLCB0d28sIHRocmVl
toStringOutput	String	one, two, three
toJsonOutput	Object	{"one": "a", "two": "b"}

concat

concat(arg1, arg2, arg3, ...)

Combines multiple string values and returns the concatenated string, or combines multiple arrays and returns the concatenated array. To improve readability, use string interpolation instead of the concat() function. However, in some cases such as string replacement in multi-line strings, you may need to fall back on using the concat() function or the replace() function.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
arg1	Yes	string or array	The first string or array for concatenation.
more arguments	No	string or array	More strings or arrays in sequential order for concatenation.

This function can take any number of arguments, and can accept either strings or arrays for the parameters. However, you can't provide both arrays and strings for parameters. Strings are only concatenated with other strings.

Return value

A string or array of concatenated values.

Examples

The following example shows a comparison between using interpolation and using the concat() function. The two outputs return the same value.

param prefix string = 'prefix'

output concatOutput string = concat(prefix, 'And', uniqueString(resourceGroup().id))
output interpolationOutput string = '${prefix}And${uniqueString(resourceGroup().id)}'

The outputs from the preceding example with the default value are:

Name	Type	Value
concatOutput	String	prefixAnd5yj4yjf5mbg72
interpolationOutput	String	prefixAnd5yj4yjf5mbg72

Interpolation is not currently supported in multi-line strings. The following example shows a comparison between using interpolation and using the concat() function.

var blocked = 'BLOCKED'

output concatOutput string = concat('''interpolation
is ''', blocked)
output interpolationOutput string = '''interpolation
is ${blocked}'''

The output from the preceding example with the default values is:

Name	Type	Value
concatOutput	String	interpolation\nis BLOCKED
interpolationOutput	String	interpolation\nis ${blocked}

contains

contains(container, itemToFind)

Checks whether an array contains a value, an object contains a key, or a string contains a substring. The string comparison is case-sensitive. However, when testing if an object contains a key, the comparison is case-insensitive.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
container	Yes	array, object, or string	The value that contains the value to find.
itemToFind	Yes	string or int	The value to find.

Return value

True if the item is found; otherwise, False.

Examples

The following example shows how to use contains with different types:

param stringToTest string = 'OneTwoThree'
param objectToTest object = {
  one: 'a'
  two: 'b'
  three: 'c'
}
param arrayToTest array = [
  'one'
  'two'
  'three'
]

output stringTrue bool = contains(stringToTest, 'e')
output stringFalse bool = contains(stringToTest, 'z')
output objectTrue bool = contains(objectToTest, 'one')
output objectFalse bool = contains(objectToTest, 'a')
output arrayTrue bool = contains(arrayToTest, 'three')
output arrayFalse bool = contains(arrayToTest, 'four')

The output from the preceding example with the default values is:

Name	Type	Value
stringTrue	Bool	True
stringFalse	Bool	False
objectTrue	Bool	True
objectFalse	Bool	False
arrayTrue	Bool	True
arrayFalse	Bool	False

dataUri

dataUri(stringToConvert)

Converts a value to a data URI.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToConvert	Yes	string	The value to convert to a data URI.

Return value

A string formatted as a data URI.

Examples

The following example converts a value to a data URI, and converts a data URI to a string:

param stringToTest string = 'Hello'
param dataFormattedString string = 'data:;base64,SGVsbG8sIFdvcmxkIQ=='

output dataUriOutput string = dataUri(stringToTest)
output toStringOutput string = dataUriToString(dataFormattedString)

The output from the preceding example with the default values is:

Name	Type	Value
dataUriOutput	String	data:text/plain;charset=utf8;base64,SGVsbG8=
toStringOutput	String	Hello, World!

dataUriToString

dataUriToString(dataUriToConvert)

Converts a data URI formatted value to a string.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
dataUriToConvert	Yes	string	The data URI value to convert.

Return value

A string containing the converted value.

Examples

The following example converts a value to a data URI, and converts a data URI to a string:

param stringToTest string = 'Hello'
param dataFormattedString string = 'data:;base64,SGVsbG8sIFdvcmxkIQ=='

output dataUriOutput string = dataUri(stringToTest)
output toStringOutput string = dataUriToString(dataFormattedString)

The output from the preceding example with the default values is:

Name	Type	Value
dataUriOutput	String	data:text/plain;charset=utf8;base64,SGVsbG8=
toStringOutput	String	Hello, World!

empty

empty(itemToTest)

Determines if an array, object, or string is empty or null.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
itemToTest	Yes	array, object, or string	The value to check if it's empty or null.

Return value

Returns True if the value is empty or null; otherwise, False.

Examples

The following example checks whether an array, object, and string are empty.

param testArray array = []
param testObject object = {}
param testString string = ''
param testNullString string?

output arrayEmpty bool = empty(testArray)
output objectEmpty bool = empty(testObject)
output stringEmpty bool = empty(testString)
output stringNull bool = empty(testNullString)

The output from the preceding example with the default values is:

Name	Type	Value
arrayEmpty	Bool	True
objectEmpty	Bool	True
stringEmpty	Bool	True
stringNull	Bool	True

endsWith

endsWith(stringToSearch, stringToFind)

Determines whether a string ends with a value. The comparison is case-insensitive.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToSearch	Yes	string	The value that contains the item to find.
stringToFind	Yes	string	The value to find.

Return value

True if the last character or characters of the string match the value; otherwise, False.

Examples

The following example shows how to use the startsWith and endsWith functions:

output startsTrue bool = startsWith('abcdef', 'ab')
output startsCapTrue bool = startsWith('abcdef', 'A')
output startsFalse bool = startsWith('abcdef', 'e')
output endsTrue bool = endsWith('abcdef', 'ef')
output endsCapTrue bool = endsWith('abcdef', 'F')
output endsFalse bool = endsWith('abcdef', 'e')

The output from the preceding example with the default values is:

Name	Type	Value
startsTrue	Bool	True
startsCapTrue	Bool	True
startsFalse	Bool	False
endsTrue	Bool	True
endsCapTrue	Bool	True
endsFalse	Bool	False

first

first(arg1)

Returns the first character of the string, or first element of the array. If an empty string is given, the function results in an empty string. In the case of an empty array, the function returns null.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
arg1	Yes	array or string	The value to retrieve the first element or character.

Return value

A string of the first character, or the type (string, int, array, or object) of the first element in an array.

Examples

The following example shows how to use the first function with an array and string.

param arrayToTest array = [
  'one'
  'two'
  'three'
]

output arrayOutput string = first(arrayToTest)
output stringOutput string = first('One Two Three')

The output from the preceding example with the default values is:

Name	Type	Value
arrayOutput	String	one
stringOutput	String	O

format

format(formatString, arg1, arg2, ...)

Creates a formatted string from input values.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
formatString	Yes	string	The composite format string.
arg1	Yes	string, integer, or boolean	The value to include in the formatted string.
additional arguments	No	string, integer, or boolean	Additional values to include in the formatted string.

Remarks

Use this function to format a string in your Bicep file. It uses the same formatting options as the System.String.Format method in .NET.

Examples

The following example shows how to use the format function.

param greeting string = 'Hello'
param name string = 'User'
param numberToFormat int = 8175133
param objectToFormat object = { prop: 'value' }

output formatTest string = format('{0}, {1}. Formatted number: {2:N0}', greeting, name, numberToFormat)
output formatObject string = format('objectToFormat: {0}', objectToFormat)

The output from the preceding example with the default values is:

Name	Type	Value
formatTest	String	`Hello, User. Formatted number: 8,175,133`
formatObject	String	`objectToFormat: {'prop':'value'}`

guid

guid(baseString, ...)

Creates a value in the format of a globally unique identifier based on the values provided as parameters.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
baseString	Yes	string	The value used in the hash function to create the GUID.
additional parameters as needed	No	string	You can add as many strings as needed to create the value that specifies the level of uniqueness.

Remarks

This function is helpful when you need to create a value in the format of a globally unique identifier. You provide parameter values that limit the scope of uniqueness for the result. You can specify whether the name is unique down to subscription, resource group, or deployment.

The returned value isn't a random string, but rather the result of a hash function on the parameters. The returned value is 36 characters long. It isn't globally unique. To create a new GUID that isn't based on that hash value of the parameters, use the newGuid function.

Note

The order of the parameters affects the returned value. For example:

guid('hello', 'world') and guid('world', 'hello')

don't return the same value.

The following examples show how to use guid to create a unique value for commonly used levels.

Unique scoped to subscription

guid(subscription().subscriptionId)

Unique scoped to resource group

guid(resourceGroup().id)

Unique scoped to deployment for a resource group

guid(resourceGroup().id, deployment().name)

The guid function implements the algorithm from RFC 4122 §4.3. The original source can be found in GuidUtility with some modifications.

Return value

A string containing 36 characters in the format of a globally unique identifier.

Examples

The following example returns results from guid:

output guidPerSubscription string = guid(subscription().subscriptionId)
output guidPerResourceGroup string = guid(resourceGroup().id)
output guidPerDeployment string = guid(resourceGroup().id, deployment().name)

indexOf

indexOf(stringToSearch, stringToFind)

Returns the first position of a value within a string. The comparison is case-insensitive.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToSearch	Yes	string	The value that contains the item to find.
stringToFind	Yes	string	The value to find.

Return value

An integer that represents the position of the item to find. The value is zero-based. If the item isn't found, -1 is returned.

Examples

The following example shows how to use the indexOf and lastIndexOf functions:

output firstT int = indexOf('test', 't')
output lastT int = lastIndexOf('test', 't')
output firstString int = indexOf('abcdef', 'CD')
output lastString int = lastIndexOf('abcdef', 'AB')
output notFound int = indexOf('abcdef', 'z')

The output from the preceding example with the default values is:

Name	Type	Value
firstT	Int	0
lastT	Int	3
firstString	Int	2
lastString	Int	0
notFound	Int	-1

join

join(inputArray, delimiter)

Joins a string array into a single string, separated using a delimiter.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
inputArray	Yes	An array of string.	An array of strings to join.
delimiter	Yes	The delimiter to use for splitting the string.

Return value

A string.

Examples

The following example joins the input string array into strings delimited by either a comma or a semi-colon.

var arrayString = [
  'one'
  'two'
  'three'
]

output firstOutput string = join(arrayString, ',')
output secondOutput string = join(arrayString, ';')

The output from the preceding example with the default values is:

Name	Type	Value
firstOutput	String	"one,two,three"
secondOutput	String	"one;two;three"

This function requires Bicep CLI version 0.8.X or higher.

json

json(arg1)

Converts a valid JSON string into a JSON data type. For more information, see json function.

Namespace: sys.

last

last(arg1)

Returns last character of the string, or the last element of the array.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
arg1	Yes	array or string	The value to retrieve the last element or character.

Return value

A string of the last character, or the type (string, int, array, or object) of the last element in an array.

Examples

The following example shows how to use the last function with an array and string.

param arrayToTest array = [
  'one'
  'two'
  'three'
]

output arrayOutput string = last(arrayToTest)
output stringOutput string = last('One Two Three')

The output from the preceding example with the default values is:

Name	Type	Value
arrayOutput	String	three
stringOutput	String	e

lastIndexOf

lastIndexOf(stringToSearch, stringToFind)

Returns the last position of a value within a string. The comparison is case-insensitive.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToSearch	Yes	string	The value that contains the item to find.
stringToFind	Yes	string	The value to find.

Return value

An integer that represents the last position of the item to find. The value is zero-based. If the item isn't found, -1 is returned.

Examples

The following example shows how to use the indexOf and lastIndexOf functions:

output firstT int = indexOf('test', 't')
output lastT int = lastIndexOf('test', 't')
output firstString int = indexOf('abcdef', 'CD')
output lastString int = lastIndexOf('abcdef', 'AB')
output notFound int = indexOf('abcdef', 'z')

The output from the preceding example with the default values is:

Name	Type	Value
firstT	Int	0
lastT	Int	3
firstString	Int	2
lastString	Int	0
notFound	Int	-1

length

length(string)

Returns the number of characters in a string, elements in an array, or root-level properties in an object.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
arg1	Yes	array, string, or object	The array to use for getting the number of elements, the string to use for getting the number of characters, or the object to use for getting the number of root-level properties.

Return value

An int.

Examples

The following example shows how to use length with an array and string:

param arrayToTest array = [
  'one'
  'two'
  'three'
]
param stringToTest string = 'One Two Three'
param objectToTest object = {
  propA: 'one'
  propB: 'two'
  propC: 'three'
  propD: {
    'propD-1': 'sub'
    'propD-2': 'sub'
  }
}

output arrayLength int = length(arrayToTest)
output stringLength int = length(stringToTest)
output objectLength int = length(objectToTest)

The output from the preceding example with the default values is:

Name	Type	Value
arrayLength	Int	3
stringLength	Int	13
objectLength	Int	4

newGuid

newGuid()

Returns a value in the format of a globally unique identifier. This function can only be used in the default value for a parameter.

Namespace: sys.

Remarks

You can only use this function within an expression for the default value of a parameter. Using this function anywhere else in a Bicep file returns an error. The function isn't allowed in other parts of the Bicep file because it returns a different value each time it's called. Deploying the same Bicep file with the same parameters wouldn't reliably produce the same results.

The newGuid function differs from the guid function because it doesn't take any parameters. When you call guid with the same parameters, it returns the same identifier each time. Use guid when you need to reliably generate the same GUID for a specific environment. Use newGuid when you need a different identifier each time, such as deploying resources to a test environment.

The newGuid function uses the Guid structure in the .NET Framework to generate the globally unique identifier.

If you use the option to redeploy an earlier successful deployment, and the earlier deployment includes a parameter that uses newGuid, the parameter isn't reevaluated. Instead, the parameter value from the earlier deployment is automatically reused in the rollback deployment.

In a test environment, you may need to repeatedly deploy resources that only live for a short time. Rather than constructing unique names, you can use newGuid with uniqueString to create unique names.

Be careful redeploying a Bicep file that relies on the newGuid function for a default value. When you redeploy and don't provide a value for the parameter, the function is reevaluated. If you want to update an existing resource rather than create a new one, pass in the parameter value from the earlier deployment.

Return value

A string containing 36 characters in the format of a globally unique identifier.

Examples

The following example shows a parameter with a new identifier.

param guidValue string = newGuid()

output guidOutput string = guidValue

The output from the preceding example varies for each deployment but will be similar to:

Name	Type	Value
guidOutput	string	b76a51fc-bd72-4a77-b9a2-3c29e7d2e551

The following example uses the newGuid function to create a unique name for a storage account. This Bicep file might work for test environment where the storage account exists for a short time and isn't redeployed.

param guidValue string = newGuid()

var storageName = 'storage${uniqueString(guidValue)}'

resource myStorage 'Microsoft.Storage/storageAccounts@2023-04-01' = {
  name: storageName
  location: 'West US'
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'StorageV2'
  properties: {}
}

output nameOutput string = storageName

The output from the preceding example varies for each deployment but will be similar to:

Name	Type	Value
nameOutput	string	storagenziwvyru7uxie

padLeft

padLeft(valueToPad, totalLength, paddingCharacter)

Returns a right-aligned string by adding characters to the left until reaching the total specified length.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
valueToPad	Yes	string or int	The value to right-align.
totalLength	Yes	int	The total number of characters in the returned string.
paddingCharacter	No	single character	The character to use for left-padding until the total length is reached. The default value is a space.

If the original string is longer than the number of characters to pad, no characters are added.

Return value

A string with at least the number of specified characters.

Examples

The following example shows how to pad the user-provided parameter value by adding the zero character until it reaches the total number of characters.

param testString string = '123'

output stringOutput string = padLeft(testString, 10, '0')

The output from the preceding example with the default values is:

Name	Type	Value
stringOutput	String	0000000123

replace

replace(originalString, oldString, newString)

Returns a new string with all instances of one string replaced by another string.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
originalString	Yes	string	The value that has all instances of one string replaced by another string.
oldString	Yes	string	The string to be removed from the original string.
newString	Yes	string	The string to add in place of the removed string.

Return value

A string with the replaced characters.

Examples

The following example shows how to remove all dashes from the user-provided string, and how to replace part of the string with another string.

param testString string = '123-123-1234'

output firstOutput string = replace(testString, '-', '')
output secondOutput string = replace(testString, '1234', 'xxxx')

The output from the preceding example with the default values is:

Name	Type	Value
firstOutput	String	1231231234
secondOutput	String	123-123-xxxx

skip

skip(originalValue, numberToSkip)

Returns a string with all the characters after the specified number of characters, or an array with all the elements after the specified number of elements.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
originalValue	Yes	array or string	The array or string to use for skipping.
numberToSkip	Yes	int	The number of elements or characters to skip. If this value is 0 or less, all the elements or characters in the value are returned. If it's larger than the length of the array or string, an empty array or string is returned.

Return value

An array or string.

Examples

The following example skips the specified number of elements in the array, and the specified number of characters in a string.

param testArray array = [
  'one'
  'two'
  'three'
]
param elementsToSkip int = 2
param testString string = 'one two three'
param charactersToSkip int = 4

output arrayOutput array = skip(testArray, elementsToSkip)
output stringOutput string = skip(testString, charactersToSkip)

The output from the preceding example with the default values is:

Name	Type	Value
arrayOutput	Array	["three"]
stringOutput	String	two three

split

split(inputString, delimiter)

Returns an array of strings that contains the substrings of the input string that are delimited by the specified delimiters.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
inputString	Yes	string	The string to split.
delimiter	Yes	string or array of strings	The delimiter to use for splitting the string.

Return value

An array of strings.

Examples

The following example splits the input string with a comma, and with either a comma or a semi-colon.

param firstString string = 'one,two,three'
param secondString string = 'one;two,three'

var delimiters = [
  ','
  ';'
]

output firstOutput array = split(firstString, ',')
output secondOutput array = split(secondString, delimiters)

The output from the preceding example with the default values is:

Name	Type	Value
firstOutput	Array	["one", "two", "three"]
secondOutput	Array	["one", "two", "three"]

startsWith

startsWith(stringToSearch, stringToFind)

Determines whether a string starts with a value. The comparison is case-insensitive.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToSearch	Yes	string	The value that contains the item to find.
stringToFind	Yes	string	The value to find.

Return value

True if the first character or characters of the string match the value; otherwise, False.

Examples

The following example shows how to use the startsWith and endsWith functions:

output startsTrue bool = startsWith('abcdef', 'ab')
output startsCapTrue bool = startsWith('abcdef', 'A')
output startsFalse bool = startsWith('abcdef', 'e')
output endsTrue bool = endsWith('abcdef', 'ef')
output endsCapTrue bool = endsWith('abcdef', 'F')
output endsFalse bool = endsWith('abcdef', 'e')

The output from the preceding example with the default values is:

Name	Type	Value
startsTrue	Bool	True
startsCapTrue	Bool	True
startsFalse	Bool	False
endsTrue	Bool	True
endsCapTrue	Bool	True
endsFalse	Bool	False

string

string(valueToConvert)

Converts the specified value to a string. Strings are returned as-is. Other types are converted to their equivalent JSON representation. If you need to convert a string to JSON, i.e. quote/escape it, you can use substring(string([value]), 1, length(string([value]) - 2).

Namespace: sys.

Parameters

Parameter	Required	Type	Description
valueToConvert	Yes	Any	The value to convert to string. Any type of value can be converted, including objects and arrays.

Return value

A string of the converted value.

Examples

The following example shows how to convert different types of values to strings:

param testObject object = {
  valueA: 10
  valueB: 'Example Text'
}
param testArray array = [
  '\'a\''
  '"b"'
  '\\c\\'
]
param testInt int = 5
param testString string = 'foo " \' \\'

output objectOutput string = string(testObject)
output arrayOutput string = string(testArray)
output intOutput string = string(testInt)
output stringOutput string = string(testString)
output stringEscapedOutput string = substring(string([testString]), 1, length(string([testString])) - 2)

The output from the preceding example with the default values is:

Name	Type	Value
objectOutput	String	`{"valueA":10,"valueB":"Example Text"}`
arrayOutput	String	`["'a'","\"b\"","\\c\\"]`
intOutput	String	`5`
stringOutput	String	`foo " ' \`
stringEscapedOutput	String	`"foo \" ' \\"`

substring

substring(stringToParse, startIndex, length)

Returns a substring that starts at the specified character position and contains the specified number of characters.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToParse	Yes	string	The original string from which the substring is extracted.
startIndex	No	int	The zero-based starting character position for the substring.
length	No	int	The number of characters for the substring. Must refer to a location within the string. Must be zero or greater. If omitted, the remainder of the string from the start position will be returned.

Return value

The substring. Or, an empty string if the length is zero.

Remarks

The function fails when the substring extends beyond the end of the string, or when length is less than zero. The following example fails with the error "The index and length parameters must refer to a location within the string. The index parameter: '0', the length parameter: '11', the length of the string parameter: '10'.".

param inputString string = '1234567890'

var prefix = substring(inputString, 0, 11)

Examples

The following example extracts a substring from a parameter.

param testString string = 'one two three'
output substringOutput string = substring(testString, 4, 3)

The output from the preceding example with the default values is:

Name	Type	Value
substringOutput	String	two

take

take(originalValue, numberToTake)

Returns a string with the specified number of characters from the start of the string, or an array with the specified number of elements from the start of the array.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
originalValue	Yes	array or string	The array or string to take the elements from.
numberToTake	Yes	int	The number of elements or characters to take. If this value is 0 or less, an empty array or string is returned. If it's larger than the length of the given array or string, all the elements in the array or string are returned.

Return value

An array or string.

Examples

The following example takes the specified number of elements from the array, and characters from a string.

param testArray array = [
  'one'
  'two'
  'three'
]
param elementsToTake int = 2
param testString string = 'one two three'
param charactersToTake int = 2

output arrayOutput array = take(testArray, elementsToTake)
output stringOutput string = take(testString, charactersToTake)

The output from the preceding example with the default values is:

Name	Type	Value
arrayOutput	Array	["one", "two"]
stringOutput	String	on

toLower

toLower(stringToChange)

Converts the specified string to lower case.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToChange	Yes	string	The value to convert to lower case.

Return value

The string converted to lower case.

Examples

The following example converts a parameter value to lower case and to upper case.

param testString string = 'One Two Three'

output toLowerOutput string = toLower(testString)
output toUpperOutput string = toUpper(testString)

The output from the preceding example with the default values is:

Name	Type	Value
toLowerOutput	String	one two three
toUpperOutput	String	ONE TWO THREE

toUpper

toUpper(stringToChange)

Converts the specified string to upper case.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToChange	Yes	string	The value to convert to upper case.

Return value

The string converted to upper case.

Examples

The following example converts a parameter value to lower case and to upper case.

param testString string = 'One Two Three'

output toLowerOutput string = toLower(testString)
output toUpperOutput string = toUpper(testString)

The output from the preceding example with the default values is:

Name	Type	Value
toLowerOutput	String	one two three
toUpperOutput	String	ONE TWO THREE

trim

trim(stringToTrim)

Removes all leading and trailing white-space characters from the specified string.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToTrim	Yes	string	The value to trim.

Return value

The string without leading and trailing white-space characters.

Examples

The following example trims the white-space characters from the parameter.

param testString string = '    one two three   '

output return string = trim(testString)

The output from the preceding example with the default values is:

Name	Type	Value
return	String	one two three

uniqueString

uniqueString(baseString, ...)

Creates a deterministic hash string based on the values provided as parameters.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
baseString	Yes	string	The value used in the hash function to create a unique string.
additional parameters as needed	No	string	You can add as many strings as needed to create the value that specifies the level of uniqueness.

Remarks

This function is helpful when you need to create a unique name for a resource. You provide parameter values that limit the scope of uniqueness for the result. You can specify whether the name is unique down to subscription, resource group, or deployment.

The returned value isn't a random string, but rather the result of a hash function. The returned value is 13 characters long. It isn't globally unique. You may want to combine the value with a prefix from your naming convention to create a name that is meaningful. The following example shows the format of the returned value. The actual value varies by the provided parameters.

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The following examples show how to use uniqueString to create a unique value for commonly used levels.

Unique scoped to subscription

uniqueString(subscription().subscriptionId)

Unique scoped to resource group

uniqueString(resourceGroup().id)

Unique scoped to deployment for a resource group

uniqueString(resourceGroup().id, deployment().name)

The following example shows how to create a unique name for a storage account based on your resource group. Inside the resource group, the name isn't unique if constructed the same way.

resource mystorage 'Microsoft.Storage/storageAccounts@2023-04-01' = {
  name: 'storage${uniqueString(resourceGroup().id)}'
  ...
}

If you need to create a new unique name each time you deploy a Bicep file, and don't intend to update the resource, you can use the utcNow function with uniqueString. You could use this approach in a test environment. For an example, see utcNow. Note the utcNow function can only be used within an expression for the default value of a parameter.

Return value

A string containing 13 characters.

Examples

The following example returns results from uniquestring:

output uniqueRG string = uniqueString(resourceGroup().id)
output uniqueDeploy string = uniqueString(resourceGroup().id, deployment().name)

uri

uri(baseUri, relativeUri)

Creates an absolute URI by combining the baseUri and the relativeUri string.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
baseUri	Yes	string	The base uri string. Take care to observe the behavior regarding the handling of the trailing slash ('/'), as described following this table.
relativeUri	Yes	string	The relative uri string to add to the base uri string.

If baseUri ends with a trailing slash, the result is simply baseUri followed by relativeUri. If relativeUri also begins with a leading slash, the trailing slash and the leading slash will be combined into one.
If baseUri does not end in a trailing slash one of two things happens.
- If baseUri has no slashes at all (aside from the "//" near the front) the result is simply baseUri followed by relativeUri.
- If baseUri has some slashes, but doesn't end with a slash, everything from the last slash onward is removed from baseUri and the result is baseUri followed by relativeUri.

Here are some examples:

uri('http://contoso.org/firstpath', 'myscript.sh') -> http://contoso.org/myscript.sh
uri('http://contoso.org/firstpath/', 'myscript.sh') -> http://contoso.org/firstpath/myscript.sh
uri('http://contoso.org/firstpath/', '/myscript.sh') -> http://contoso.org/firstpath/myscript.sh
uri('http://contoso.org/firstpath/azuredeploy.json', 'myscript.sh') -> http://contoso.org/firstpath/myscript.sh
uri('http://contoso.org/firstpath/azuredeploy.json/', 'myscript.sh') -> http://contoso.org/firstpath/azuredeploy.json/myscript.sh

For complete details, the baseUri and relativeUri parameters are resolved as specified in RFC 3986, section 5.

Return value

A string representing the absolute URI for the base and relative values.

Examples

The following example shows how to use uri, uriComponent, and uriComponentToString:

var uriFormat = uri('http://contoso.com/resources/', 'nested/azuredeploy.json')
var uriEncoded = uriComponent(uriFormat)

output uriOutput string = uriFormat
output componentOutput string = uriEncoded
output toStringOutput string = uriComponentToString(uriEncoded)

The output from the preceding example with the default values is:

Name	Type	Value
uriOutput	String	`http://contoso.com/resources/nested/azuredeploy.json`
componentOutput	String	`http%3A%2F%2Fcontoso.com%2Fresources%2Fnested%2Fazuredeploy.json`
toStringOutput	String	`http://contoso.com/resources/nested/azuredeploy.json`

uriComponent

uricomponent(stringToEncode)

Encodes a URI.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
stringToEncode	Yes	string	The value to encode.

Return value

A string of the URI encoded value.

Examples

The following example shows how to use uri, uriComponent, and uriComponentToString:

var uriFormat = uri('http://contoso.com/resources/', 'nested/azuredeploy.json')
var uriEncoded = uriComponent(uriFormat)

output uriOutput string = uriFormat
output componentOutput string = uriEncoded
output toStringOutput string = uriComponentToString(uriEncoded)

The output from the preceding example with the default values is:

Name	Type	Value
uriOutput	String	`http://contoso.com/resources/nested/azuredeploy.json`
componentOutput	String	`http%3A%2F%2Fcontoso.com%2Fresources%2Fnested%2Fazuredeploy.json`
toStringOutput	String	`http://contoso.com/resources/nested/azuredeploy.json`

uriComponentToString

uriComponentToString(uriEncodedString)

Returns a string of a URI encoded value.

Namespace: sys.

Parameters

Parameter	Required	Type	Description
uriEncodedString	Yes	string	The URI encoded value to convert to a string.

Return value

A decoded string of URI encoded value.

Examples

The following example shows how to use uri, uriComponent, and uriComponentToString:

var uriFormat = uri('http://contoso.com/resources/', 'nested/azuredeploy.json')
var uriEncoded = uriComponent(uriFormat)

output uriOutput string = uriFormat
output componentOutput string = uriEncoded
output toStringOutput string = uriComponentToString(uriEncoded)

The output from the preceding example with the default values is:

Name	Type	Value
uriOutput	String	`http://contoso.com/resources/nested/azuredeploy.json`
componentOutput	String	`http%3A%2F%2Fcontoso.com%2Fresources%2Fnested%2Fazuredeploy.json`
toStringOutput	String	`http://contoso.com/resources/nested/azuredeploy.json`

Next steps

For a description of the sections in a Bicep file, see Understand the structure and syntax of Bicep files.
To iterate a specified number of times when creating a type of resource, see Iterative loops in Bicep.
To see how to deploy the Bicep file you've created, see Deploy resources with Bicep and Azure PowerShell.

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String functions for Bicep

base64

Parameters

Return value

Examples

base64ToJson

Parameters

Return value

Examples

base64ToString

Parameters

Return value

Examples

concat

Parameters

Return value

Examples

contains

Parameters

Return value

Examples

dataUri

Parameters

Return value

Examples

dataUriToString

Parameters

Return value

Examples

empty

Parameters

Return value

Examples

endsWith

Parameters

Return value

Examples

first

Parameters

Return value

Examples

format

Parameters

Remarks

Examples

guid

Parameters

Remarks

Return value

Examples

indexOf

Parameters

Return value

Examples

join

Parameters

Return value

Examples

json

last

Parameters

Return value

Examples

lastIndexOf

Parameters

Return value

Examples

length

Parameters

Return value

Examples

newGuid

Remarks

Return value

Examples

padLeft

Parameters

Return value

Examples