Data
Statement to store data at compile time.
Data constant_expression1 [,constant_expression2]...
Data stores a list of constant numeric or alphabetical expressions that are evaluated at compile time (except with -lang qb) and stored as constants that can be read into variables by using Read.
All the Data statements in the program behave as a single chained list; after the last element of one Data statement is read, the first element of the following Data statement will be read.
The program should not attempt to Read after the last Data element. The results are (in all dialects) undefined, and the program may crash (Page Fault).
Data statements are only visible from within the module in which they are defined.
Data constants can only be of simple types (numeric or string). A numeric value can be read as a numeric literal into a string. A string read into a numeric variable will be evaluated by the Val function. Consts can be used as items of data except in the -lang qb dialect, where their names are considered as normal text.
The "Restore label" statement makes the first Data item after the label the next item to be read, allowing the user to choose specific sections of data to read.
Data is normally used to initialize variables. FreeBASIC also allows the initialization of static variables when they are Dimensioned - see Variable Initializers for more information.
Syntax
Data constant_expression1 [,constant_expression2]...
Description
Data stores a list of constant numeric or alphabetical expressions that are evaluated at compile time (except with -lang qb) and stored as constants that can be read into variables by using Read.
All the Data statements in the program behave as a single chained list; after the last element of one Data statement is read, the first element of the following Data statement will be read.
The program should not attempt to Read after the last Data element. The results are (in all dialects) undefined, and the program may crash (Page Fault).
Data statements are only visible from within the module in which they are defined.
Data constants can only be of simple types (numeric or string). A numeric value can be read as a numeric literal into a string. A string read into a numeric variable will be evaluated by the Val function. Consts can be used as items of data except in the -lang qb dialect, where their names are considered as normal text.
The "Restore label" statement makes the first Data item after the label the next item to be read, allowing the user to choose specific sections of data to read.
Data is normally used to initialize variables. FreeBASIC also allows the initialization of static variables when they are Dimensioned - see Variable Initializers for more information.
Example
' Create an array of 5 integers and a string to hold the data.
Dim As Integer h(4)
Dim As String hs
Dim As Integer readindex
' Set up to loop 5 times (for 5 numbers... check the data)
For readindex = 0 To 4
' Read in an integer.
Read h(readindex)
' Display it.
Print "Number" ; readindex ; " = " ; h(readindex)
Next readindex
' Spacer.
Print
' Read in a string.
Read hs
' Print it.
Print "String = " + hs
' Await a keypress.
Sleep
' Exit program.
End
' Block of data.
Data 3, 234, 435/4, 23+433, 87643, "Good" + "Bye!"
Dim As Integer h(4)
Dim As String hs
Dim As Integer readindex
' Set up to loop 5 times (for 5 numbers... check the data)
For readindex = 0 To 4
' Read in an integer.
Read h(readindex)
' Display it.
Print "Number" ; readindex ; " = " ; h(readindex)
Next readindex
' Spacer.
' Read in a string.
Read hs
' Print it.
Print "String = " + hs
' Await a keypress.
Sleep
' Exit program.
End
' Block of data.
Data 3, 234, 435/4, 23+433, 87643, "Good" + "Bye!"
Dialect Differences
- -lang fb and -lang fblite considers data items as constant expressions that are evaluated during compilation and its result stored in the program.
- -lang qb considers unquoted words, including names of variables and constants, as literal strings, and stores them without change, as in QBASIC. Unquoted strings are delimited by commas, and a colon or a line-break signifies the end of the Data statement. Unquoted strings are trimmed of whitespace at the beginning and end.
Differences from QB
- Outside of the -lang qb dialect, alphabetic string literals must be enclosed within quotation marks, in QBASIC this was optional.
- In QBASIC empty items evaluated to number 0 or to empty strings, in FreeBASIC they give a compile error. In QBASIC a comma at the end of the statement made an additional, empty item, evaluated to 0 or an empty string. In FreeBASIC they give a compile error.
See also
