> For the complete documentation index, see [llms.txt](https://boxlang.ortusbooks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://boxlang.ortusbooks.com/boxlang-language/reference/built-in-functions/list/listappend.md). # ListAppend Appends an element to a list ## Method Signature ``` ListAppend(list=[string], value=[string], delimiter=[string], includeEmptyFields=[boolean], multiCharacterDelimiter=[boolean]) ``` ### Arguments | Argument | Type | Required | Description | Default | | ------------------------- | --------- | -------- | -------------------------------------------------------------- | ------- | | `list` | `string` | `true` | string list to filter entries from | | | `value` | `string` | `true` | The value to append | | | `delimiter` | `string` | `false` | string the list delimiter | `,` | | `includeEmptyFields` | `boolean` | `false` | boolean whether to include empty fields in the returned result | `false` | | `multiCharacterDelimiter` | `boolean` | `false` | boolean whether the delimiter is multi-character | `false` | ## Examples ### Simple listAppend Example Add 'foo' to the end of this list [Run Example](https://try.boxlang.io/?code=eJzLz0nxySwuUbBVUEpKLNIBYiMla6681HKoaA6QciwoSM1L0VDIh6jVUVBKy89XUtC05iovyixJ9S8tKSgtgUsrqCko6eraKQFpmDFAlQDxyCCh) ```java oldList = "bar,bar2"; newList = listAppend( oldList, "foo" ); writeOutput( oldList & "-->" & newList ); ``` Result: bar,bar2,foo ### Simple listAppend Example with Delimiter Add 'foo' to the end of this list using a custom delimiter [Run Example](https://try.boxlang.io/?code=eJzLz0nxySwuUbBVUEpKLNIBYiMla6681HKoaA6QciwoSM1L0VDIh6jVUVBKy89XAlI1Sgqa1lzlRZklqf6lJQWlJXA1CmoKSrq6dkpAGmYWUCUAhFMhrQ%3D%3D) ```java oldList = "bar,bar2"; newList = listAppend( oldList, "foo", "|" ); writeOutput( oldList & "-->" & newList ); ``` Result: bar,bar2|foo ### Simple listAppend Example with Empty Fields On Add 'foo,,' to the end of this list using includeEmptyFields as true [Run Example](https://try.boxlang.io/?code=eJzLz0nxySwuUbBVUEpKLNIBYiMla6681HKoaA6QciwoSM1L0VDIh6jVUVBKy8%2FX0VECMkBESVFpqoKmNVd5UWZJqn9pSUFpCVytgpqCkq6unRKQhpkJVAkAiv8jwQ%3D%3D) ```java oldList = "bar,bar2"; newList = listAppend( oldList, "foo,,", ",", true ); writeOutput( oldList & "-->" & newList ); ``` Result: bar,bar2,foo,, ### Simple listAppend Example with Empty Fields Off Add 'foo' to the end of this list using includeEmptyFields as false [Run Example](https://try.boxlang.io/?code=eJzLz0nxySwuUbBVUEpKLNIBYiMla6681HKoaA6QciwoSM1L0VDIh6jVUVBKy8%2FX0VECMkBEWmJOcaqCpjVXeVFmSap%2FaUlBaQlcsYKagpKurp0SkIYZClQJAK6NJAw%3D) ```java oldList = "bar,bar2"; newList = listAppend( oldList, "foo,,", ",", false ); writeOutput( oldList & "-->" & newList ); ``` Result: bar,bar2,foo ### Additional Examples [Run Example](https://try.boxlang.io/?code=eJxVjr0KAjEQhPs8xZBGheD1HhaCjc29QzCrFzA%2FJBvivb254IFWC%2FPN7IxbXjYzzpDBk%2BIaFM%2BJSI7CLZ7qF67nEiN5s4frCQX5CCVJHEYxDJgCE3jW%2FGPFPZFmytBonzo44sYwgbLfMUo0uqcI9G7Q%2Bmc3nURNlulaXNza1pY%2FcZvW9A%2BFhkMn) ```java mylist = "one,two,three"; mynewlist = listAppend( mylist, "four" ); // Note that listAppend creates a new list. It doesn't update the existing list: writeDump( mylist ); writeDump( mynewlist ); ``` [Run Example](https://try.boxlang.io/?code=eJzLrczJLC5RsFVQSsvPV7Lmyq3MSy2HCoEox4KC1LwUDYVcsDodBaWkxCIlIFWjpKBpzVVelFmS6lKaWwBSANMIFAcA50scNg%3D%3D) ```java mylist = "foo"; mynewlist = listAppend( mylist, "bar", "|" ); writeDump( mynewlist ); ``` ## Related * [GetToken](/boxlang-language/reference/built-in-functions/list/gettoken.md) * [ListAvg](/boxlang-language/reference/built-in-functions/list/listavg.md) * [ListChangeDelims](/boxlang-language/reference/built-in-functions/list/listchangedelims.md) * [ListCompact](/boxlang-language/reference/built-in-functions/list/listcompact.md) * [ListContains](/boxlang-language/reference/built-in-functions/list/listcontains.md) * [ListContainsNoCase](/boxlang-language/reference/built-in-functions/list/listcontainsnocase.md) * [ListDeleteAt](/boxlang-language/reference/built-in-functions/list/listdeleteat.md) * [ListEach](/boxlang-language/reference/built-in-functions/list/listeach.md) * [ListEvery](/boxlang-language/reference/built-in-functions/list/listevery.md) * [ListFilter](/boxlang-language/reference/built-in-functions/list/listfilter.md) * [ListFind](/boxlang-language/reference/built-in-functions/list/listfind.md) * [ListFindNoCase](/boxlang-language/reference/built-in-functions/list/listfindnocase.md) * [ListFirst](/boxlang-language/reference/built-in-functions/list/listfirst.md) * [ListGetAt](/boxlang-language/reference/built-in-functions/list/listgetat.md) * [ListGetEndings](/boxlang-language/reference/built-in-functions/list/listgetendings.md) * [ListIndexExists](/boxlang-language/reference/built-in-functions/list/listindexexists.md) * [ListInsertAt](/boxlang-language/reference/built-in-functions/list/listinsertat.md) * [ListItemTrim](/boxlang-language/reference/built-in-functions/list/listitemtrim.md) * [ListLast](/boxlang-language/reference/built-in-functions/list/listlast.md) * [ListLen](/boxlang-language/reference/built-in-functions/list/listlen.md) * [ListMap](/boxlang-language/reference/built-in-functions/list/listmap.md) * [ListNone](/boxlang-language/reference/built-in-functions/list/listnone.md) * [ListPrepend](/boxlang-language/reference/built-in-functions/list/listprepend.md) * [ListQualify](/boxlang-language/reference/built-in-functions/list/listqualify.md) * [ListReduceRight](/boxlang-language/reference/built-in-functions/list/listreduceright.md) * [ListRemoveDuplicates](/boxlang-language/reference/built-in-functions/list/listremoveduplicates.md) * [ListRest](/boxlang-language/reference/built-in-functions/list/listrest.md) * [ListSetAt](/boxlang-language/reference/built-in-functions/list/listsetat.md) * [ListSome](/boxlang-language/reference/built-in-functions/list/listsome.md) * [ListSort](/boxlang-language/reference/built-in-functions/list/listsort.md) * [ListToArray](/boxlang-language/reference/built-in-functions/list/listtoarray.md) * [ListTrim](/boxlang-language/reference/built-in-functions/list/listtrim.md) * [ListValueCount](/boxlang-language/reference/built-in-functions/list/listvaluecount.md) * [ListValueCountNoCase](/boxlang-language/reference/built-in-functions/list/listvaluecountnocase.md) --- # Agent Instructions This documentation is published with GitBook. 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