Что такое формат файла PRG?
.prg is a source-code file associated primarily with the xBase family of database-programming languages, including dBASE, FoxPro, Visual FoxPro, Clipper, and the modern open-source Harbour compiler. A .prg file is also a generic extension used by various programs to store macros or program instructions; such files are not standardized and serve different purposes depending on the application.
In its dominant xBase role, a .prg stores plain-text source code - not binary data - making it readable in any text editor. A typical program begins with comment lines (prefixed with * or &&), SET directives, and PROCEDURE/FUNCTION blocks that operate on .dbf database tables. When compiled, FoxPro produces a binary .fxp object file, while Clipper and Harbour generate a native executable; the .prg source itself is always human-readable. The xBase language traces back to dBASE II/III in the early 1980s and dominated desktop-database programming through the 1990s. Visual FoxPro 9.0 SP2 (2007) was the last major commercial release; the language lives on through the open-source Harbour project.
.prg files are sometimes used by programmers or university lecturers for educational or testing purposes. Such files may store pseudocode - an informal, high-level description of a computer program or algorithm in plain text. Pseudocode is an abstraction, not an implementation, of a computer program; it contains standard control instructions such as loops or conditional expressions in human-readable rather than machine-readable format. Pseudocode is language-independent and cannot be executed on a computer. .prg files are sometimes chosen for pseudocode precisely because the extension does not refer to any actual programming language.
Безопасность и защита
РИСК: MEDIUMA .prg is plain-text source code, so the file itself can't execute by being opened in an editor - reading one is safe. The risk is in what it does when run/compiled: xBase code can run shell commands (RUN/!), read and write database files, and delete data, so don't blindly DO or compile an untrusted .prg. Read the source first, run legacy apps in an isolated/VM environment, and be wary of programs that touch .dbf data you care about. (The unrelated GEM/Atari .prg is a true binary executable - treat any .prg that is binary, not text, with extra caution.)
Детали формата
в двух словах- GEM / Atari ST program - On Atari ST and GEM/DOS, .prg is an executable PROGRAM file (a true binary), not source code.
- Lotus 1-2-3 / Symphony program - Some Lotus and other DOS-era apps used .prg for macro/program scripts.
- MicroSim PCBoard / WAVmaker file - A few engineering and music tools reused .prg for their own data; rare and unrelated to xBase.
Программы, открывающие файлы PRG
Windows5 apps
Notepad
Открытый код Open the .prg to read/edit the source as text; an xBase/Clipper syntax-highlighting UDL can be added. 
Visual Studio Code
Бесплатно Open the .prg; install a FoxPro/Harbour language extension for syntax highlighting. 
Microsoft Visual FoxPro (legacy)
Платно Open the project and run/modify the .prg, or compile it (DO program.prg / build to .app/.exe). Discontinued 2007 - legacy use only.
Harbour compiler
Открытый код Compile the xBase source: 'harbour program.prg' then link into a native executable (hbmk2 program.prg). 
macOS2 apps
Visual Studio Code
Бесплатно Open the .prg; install a FoxPro/Harbour language extension for syntax highlighting.
Harbour compiler
Открытый код Compile the xBase source: 'harbour program.prg' then link into a native executable (hbmk2 program.prg). 
Linux2 apps
Harbour / xHarbour
Открытый код Compile and link the .prg into a native Linux executable (hbmk2 program.prg); the main way to keep xBase apps alive today.
Any text editor (gedit, VS Code, Vim)
Бесплатно Open the .prg as plain text to read or edit the source. Технические подробности
глубокая спецификация| File type | Plain-text xBase (dBASE/FoxPro/Clipper) source code |
| MIME type | text/plain; also seen as text/x-prg |
| Character encoding | ASCII / Windows-1252 for Western locales; legacy OEM DOS codepage in older Eastern European files |
| File signature (magic bytes) | None - plain text with no binary header; programs typically open with comment lines (* or &&), SET directives, or a PROCEDURE/FUNCTION declaration |
| Typical file size | 1 KB to a few hundred KB of source text |
| Compilation output | FoxPro/VFP compiles .prg to a binary .fxp object file; Clipper and Harbour compile to a native executable |
| Companion data format | .dbf - xBase programs are tightly coupled to dBASE table files for data storage and retrieval |
| Compression | None in source form |
| Encryption / distribution | Source .prg is unencrypted plain text; FoxPro can encrypt compiled .app output for commercial distribution |
| Language dialect variants | dBASE III/IV, FoxPro 2.x, Visual FoxPro 6-9 (OOP extensions), Clipper 5.x, Harbour, xHarbour - same .prg extension with subtly differing syntax |
| Comment syntax | Line comments begin with * (asterisk at line start) or && (inline); NOTE keyword is also valid |
| Object-oriented support | Visual FoxPro introduced DEFINE CLASS / ENDDEFINE blocks inside .prg files, enabling OOP alongside procedural code |
| Control flow keywords | IF/ENDIF, DO WHILE/ENDDO, FOR/NEXT, DO CASE/ENDCASE, SCAN/ENDSCAN - xBase-specific syntax |
| OS support | Originally DOS and Windows (dBASE, FoxPro, VFP); Harbour enables Linux and macOS compilation from the same .prg source |
| Current ecosystem | Commercial tools discontinued (Visual FoxPro 9.0 SP2 was the last, 2007); actively maintained via open-source Harbour and xHarbour projects |
| Выпущен | early 1980s with dBASE II/III; adopted by FoxPro, Clipper and later Visual FoxPro |
| Последняя версия | Visual FoxPro 9.0 SP2 (2007) was the last major host; the language lives on in open-source Harbour |
| Открыть стандартное | Да · без роялти |
| Спецификация | learn.microsoft.com |
Конвертации PRG
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