xBase3

A dBASE III+ compatible database system written in C.

dBASE was originally created by Ashton-Tate (1979) and later developed by Borland. xBase3 is an independent open-source implementation.

Features

• Full DBF Support: Read and write standard dBASE III+ .DBF files
• XDX Index Engine: Custom B-tree index format for fast lookups
• Interactive REPL: Classic dot-prompt interface
• Expression Evaluator: Arithmetic, string, logical, and relational operations
• Built-in Functions: String, numeric, date, and conversion functions
• Memory Variables: PUBLIC, PRIVATE, and LOCAL scope support

Building

Requirements

• C11 compatible compiler (clang or gcc)
• Make or CMake

Build with Make

make

Build with CMake

cmake -B build
cmake --build build

Run Tests

make test

Usage

Interactive Mode

./build/xbase3

Run a Script

./build/xbase3 script.prg

Execute Single Command

./build/xbase3 -c "? 1 + 2"

Supported Commands

Command	Description
CREATE <file>	Create new database (interactive field definition)
USE <file>	Open database file
CLOSE	Close current database
APPEND BLANK	Add new blank record
REPLACE <field> WITH <value>	Update field value
DELETE / RECALL	Mark/unmark record as deleted
PACK	Remove deleted records
ZAP	Delete all records
GO <n> / GO TOP / GO BOTTOM	Navigate to record
SKIP [n]	Move forward/backward
LIST / DISPLAY	Show records
LOCATE FOR <condition>	Find record
CONTINUE	Find next matching record
INDEX ON <expr> TO <file>	Create index on expression
SET INDEX TO <file>	Open existing index
SET ORDER TO <n>	Select controlling index
SEEK <value>	Find record by index key
REINDEX	Rebuild open indexes
CLOSE INDEXES	Close all indexes
? / ??	Print expressions
STORE <value> TO <var>	Assign variable
QUIT	Exit program

Supported Field Types

Type	Description	Example
C	Character	name,C,30
N	Numeric	age,N,3,0 or price,N,10,2
D	Date	birthdate,D,8
L	Logical	active,L,1
M	Memo	notes,M,10

Built-in Functions

String Functions

• LEN(), TRIM(), LTRIM(), RTRIM()
• UPPER(), LOWER()
• SUBSTR(), LEFT(), RIGHT()
• AT(), STUFF(), SPACE(), REPLICATE()

Numeric Functions

• ABS(), INT(), ROUND()
• SQRT(), MOD(), MAX(), MIN()

Date Functions

• DATE(), YEAR(), MONTH(), DAY()
• DOW(), CDOW(), CMONTH()
• DTOC(), CTOD()

Conversion Functions

• STR(), VAL(), CHR(), ASC()

Database Functions

• RECNO(), RECCOUNT(), EOF(), BOF()
• DELETED(), FIELD(), FCOUNT()

Other Functions

• IIF(), TYPE(), EMPTY()

Example Session

xBase3 version 0.1.0
dBASE III+ Compatible Database System
Type QUIT to exit, ? expr to evaluate

. CREATE employees
Enter fields (name,type,length[,decimals]) - blank line to finish:
Field 1: name,C,30
Field 2: salary,N,10,2
Field 3:
Database employees.dbf created with 2 field(s)
EMPLOYEES> APPEND BLANK
Record 1 appended
EMPLOYEES> REPLACE name WITH "John Doe", salary WITH 50000
1 record(s) replaced
EMPLOYEES> APPEND BLANK
Record 2 appended
EMPLOYEES> REPLACE name WITH "Jane Smith", salary WITH 60000
1 record(s) replaced
EMPLOYEES> LIST
       1   John Doe                       50000.00
       2   Jane Smith                     60000.00
EMPLOYEES> ? SUM(salary)
110000.00
EMPLOYEES> QUIT

File Formats

DBF (Database Files)

Standard dBASE III+ format - fully compatible with other dBASE implementations.

XDX (Index Files)

Custom B-tree index format:

• 512-byte header with key expression, type, and flags
• B-tree nodes with configurable order (default: 50 keys per node)
• Supports Character, Numeric, and Date key types
• Optional UNIQUE and DESCENDING flags

Index Example

. USE customers
CUSTOMERS> INDEX ON name TO custname UNIQUE
100 record(s) indexed
CUSTOMERS> SEEK "Smith"
Found at record 42
CUSTOMERS> ? NAME
Smith, John
CUSTOMERS> SET INDEX TO
Indexes closed

License

MIT License

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.