# Default File Variables The following statements make use of a feature known as default file variables: clearfile delete matread matreadu matwrite matwriteu open read readu readv readvu release select write writev writevu Note: Most experts agree that use of this feature should be avoided as it makes program maintenance more difficult, but here is a discussion of how they work. When a file is opened with an open statement, it is usually assigned to a file variable for referencing the file later in the program with any of the above statements. This takes the general form: ``` open "customers" to customer.file else... ``` The operative word here is to. In this case, it assigns the actual location (represented internally as a base, modulo and separation) to the customer file variable. Later in the program, when an item is read from the file, the file variable displays in the appropriate form of a read statement, as in the form: ``` read customer.item from customer.file else... ``` Here, the operative word is from. With default file variables, nothing is explicitly assigned during the open statement, as in the form: ``` open "customers" else... ``` Therefore, any subsequent attempt to read from or write to the file does not require the file variable reference, as illustrated in the form: ``` read customer.item else... ``` There can be only one default file variable in a BASIC program. Any subsequent file needed for input or output must have an explicitly assigned file variable during the open statement, or it takes the place of the default file. ## See also - [base](https://d3codex.com/attributedefiningitem/base/) - [clear statement](https://d3codex.com/pickbasic-flashbasic/clear-statement/) - [clearfile statement](https://d3codex.com/pickbasic-flashbasic/clearfile-statement/) - [close statement](https://d3codex.com/pickbasic-flashbasic/close-statement/) - [common statement](https://d3codex.com/pickbasic-flashbasic/common-statement/) - [convert statement](https://d3codex.com/pickbasic-flashbasic/convert-statement/) - [convert() function](https://d3codex.com/pickbasic-flashbasic/convert-function/) - [Data representation](https://d3codex.com/pickbasic-flashbasic/data-representation/) - [delete statement](https://d3codex.com/pickbasic-flashbasic/delete-statement/) - [clearfile statement](https://d3codex.com/pickbasic-flashbasic/clearfile-statement/) - [matread statement](https://d3codex.com/pickbasic-flashbasic/matread-statement/) - [matwrite statement](https://d3codex.com/pickbasic-flashbasic/matwrite-statement/) - [matwriteu statement](https://d3codex.com/pickbasic-flashbasic/matwriteu-statement/) - [open statement](https://d3codex.com/pickbasic-flashbasic/open-statement/) - [read statement](https://d3codex.com/pickbasic-flashbasic/read-statement/) - [readv statement](https://d3codex.com/pickbasic-flashbasic/readv-statement/) - [release statement](https://d3codex.com/pickbasic-flashbasic/release-statement/) - [Reserved words](https://d3codex.com/pickbasic-flashbasic/reserved-words/) - [clearselect statement](https://d3codex.com/pickbasic-flashbasic/clearselect-statement/) - [write statement](https://d3codex.com/pickbasic-flashbasic/write-statement/) - [writev statement](https://d3codex.com/pickbasic-flashbasic/writev-statement/) - [writevu statement](https://d3codex.com/pickbasic-flashbasic/writevu-statement/) --- Source: https://d3codex.com/pickbasic-flashbasic/default-file-variables/ - part of the D3Codex reference.