ComputerCraft Wiki - User contributions [en]

Fs.open

2016-06-09T21:08:21Z

Randomdude999: More use of Template:Type

{{lowercase}}
{{Function
|name=fs.open
|args={{Type|string}} path, {{Type|string}} mode
|api=fs
|returns={{Type|table}} the file handle, or {{Type|nil}} on error (e.g. if <var>mode</var> was "r" and the file did not exist, or if <var>mode</var> was "w" or "a" and the file was in a read-only location)
|desc=
'''Supported File Modes'''
Opens a file so it can be read or written. <var>mode</var> consists of a first character which is one of the following:
* "r" to open the file read-only,
* "w" to open it for writing and remove any existing data on file open, or
* "a" to open for writing but keep existing data and append any writes to the end of the file
Any of the three may be optionally followed by "b" to open the file for binary access instead of the default text access (eg, "wb" opens a file for binary output).

Text mode file handles assume UTF-8 encoding for both input and output purposes, and supports all characters within the [https://en.wikipedia.org/wiki/ISO/IEC_8859-1 ISO 8859-1 codepage] (plus a few extras). Prior to ComputerCraft 1.76, instead only [https://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters printable ASCII] characters are supported. In either case, any characters ''not'' supported are translated to 0x3F (representing a question mark).

When you have opened a file you must always [[#Closing a file handle|close the file handle]], or else data may not be saved.

Append mode and write mode both create a new file if none already exists (and write mode creates a new one even if one does); however, under a few builds of ComputerCraft in the 1.5x range, append mode will fail if an existing file cannot be found.
|examples=
{{Example
|desc=Creates the file "abcd" for writing, and holds a file handle to it
|code=local h = fs.open("abcd", "w")
}}
{{Example
|desc=Opens "abcd" in either append or write mode, depending on whether it already exists or not.
|code=local h = fs.open("abcd", fs.exists("abcd") and "a" or "w")
}}
}}

== File Handles ==

A file handle allows access to a file. A file handle is a table; the functions within the table are accessed with the dot operator (<em>not</em> the colon operator, as may be more intuitive!). The examples below assume a file has already been opened and the handle stored in the variable <var>h</var>.

=== Closing a file handle ===

When you open a file you must remember to close the handle when you've finished with it! The write modes supported by ComputerCraft may not actually output data until this is done. A file opened in any mode exposes the following close function:
{{Function
|name=<var>h</var>.close
|api=fs
|desc=Closes the file handle, after which it can no longer be used
}}

=== Files opened in text read mode ===

A file opened in mode "r" (text read mode) exposes the following functions.

{{Function
|name=<var>h</var>.readLine
|api=fs
|returns={{type|string}} the next line read from the file, with the end-of-line character stripped; or nil if there are no more lines in the file
|desc=Reads the next line from the file
}}
{{Function
|name=<var>h</var>.readAll
|api=fs
|returns={{type|string}} the entire rest of the file, with the end-of-line character on the very last line (if present) stripped
|desc=Reads the all the text in the file
}}

=== Files opened in text write/append mode ===

A file opened in mode "w" (text write mode) or "a" (text append mode) exposes the following functions:

{{Function
|name=<var>h</var>.write
|args={{type|string}} data
|api=fs
|desc=Writes a string of characters to the file exactly as they appear in the string <var>data</var>
}}
{{Function
|name=<var>h</var>.writeLine
|args={{type|string}} data
|api=fs
|desc=Writes a string of characters to the file, then appends an end-of-line character
}}
if you just want to save a file, without closing the handle, then you could do a flush. ( this is normally used for logging etc...)
{{Function
|name=<var>h</var>.flush
|api=fs
|desc=Flushes the data to the specified file. (keeps the handle available afterwards)
}}

=== Files opened in binary read mode ===

A file opened in mode "rb" (binary read mode) exposes the following functions:

{{Function
|name=<var>h</var>.read
|api=fs
|returns={{type|number}} the byte read from the file, or {{type|nil}} if there are no more bytes
|desc=Reads a single byte from the file and returns it
}}

=== Files opened in binary write/append mode ===

A file opened in mode "wb" (binary write mode) or "ab" (binary append mode) exposes the following functions:

{{Function
|name=<var>h</var>.write
|args={{type|number}} byte
|api=fs
|desc=Writes a single byte into the file
}}

[[Category:Lua_Core_Functions]]

Pastebin (program)

2015-10-19T07:14:05Z

Randomdude999: Created

<code>pastebin</code> is a program installed on computers since ComputerCraft 1.31. It makes use of the <code>http</code> API to connect to, as the name implies, Pastebin.com. It can be used to either get programs from pastebin, upload them to pastebin or download and run programs on the fly.

{{Example
|desc=Download the code under Pastebin id WmFHmuZq and save it as 'LyqydOS'.
|code=pastebin get WmFHmuZq LyqydOS
}}
{{Example
|desc=Upload the program 'test3' to Pastebin. It will print a Pastebin id into the chat which can then be used to access it later, either from the browser or the pastebin program.
|code=pastebin put test3
}}
{{Example
|desc=Download the code under the Pastebin id WmFHmuZq, run it and then delete the downloaded file. (Useful for installers)
|code=pastebin run WmFHmuZq
}}

Treasure Disks

2015-10-18T20:31:14Z

Randomdude999: Created

Treasure Disks are floppy disks added in 1.56 found only in random loot chests. (Ie. dungeon chests, village blacksmith chests, mineshaft chest carts,strongholds) They contain a random program by the community. The programs were chosen [http://www.computercraft.info/forums2/index.php?/topic/14293-wanted-the-best-community-made-programs-to-include-in-computercraft-seeking-submissions/ on the forums] in 2013, but as of 18.10.2015 the thread is still pinned in Programs.

==Table of programs==

{| class="wikitable"
! Author
! Program name
! Descrption
|-
| dan200
| alongtimeago
| An ASCII Star Wars Episode 4 recreation. Tips: Play on a monitor, it won't fit on a computer screen.
|-
| fredthead
| protector
| A UFO-themed game, in which you are a spaceship defending 6 humans from the UFOs by shooting (pressing space) them. Every time you hit one, you get 20 points. The more points, the faster the UFOs and the harder it is to hit them. There is a scoreboard with 5 built-in high-scores. There is Dan at 1000 points, and Fred at 800, 600, 400 and 200 points. (Note: Use the arrow keys to move / turn around)
|-
| GopherATL
| battleship
|A battleships implementation which uses 2 computers connected through either [[Wireless Modem|wireless]] or [[Wired Modem|wired modems]].
|-
| GravityScore
| LuaIDE
| An IDE which might make you actually like editing code in-game.
|-
| JTK
| maze3d
| Actually contains both maze2d and maze3d, both of which are procedurally generated maze simulators. Maze3d is actually in 3d, at the cost of being kinda hard to control.
|-
| Lyqyd
| nsh
| A remote shell.
|-
| nitrogenfingers
| goldrunner
| A platformer.
|-
| nitrogenfingers
| npaintpro
| An improvement over the standard paint program.
|-
| TheOriginalBIT
| tictactoe
| A tic-tac-toe implementation, with an AI.
|-
| vilsol
| gameoflife
| A Conway's game of life implementation, with accurate prediction, pausing and stepping.
|}

Rednet Tutorial

2015-08-05T19:14:22Z

Randomdude999: And the text under it...

Rednet is an API that allows computers and turtles interact with each other wirelessly.

== Getting started ==

* Attach a [[Wireless Modem|wireless modem]] to your [[Computer|computer]].
{{Crafting grid
|A1=stone |B1=stone |C1=stone
|A2=stone |B2=ender_pearl |C2=stone
|A3=stone |B3=stone |C3=stone
|Output=Modem
}}

A modem is made using 8 stone blocks surrounding a ender pearl.

== Rednet scripts ==
Rednet uses several methods to interact with other computers.

Here is a basic program that runs most of them. It requires 2 PCs.

PC1
[[Rednet_(API)|rednet]].[[Rednet.open|open]]("right") --enable the modem attached to the right side of the PC
[[Rednet_(API)|rednet]].[[Rednet.broadcast|broadcast]]("Hello world") --send "Hello world" over rednet to all PCs in range
[[print]]("PC1 - Hello world")
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]]() --wait until something is received over rednet
if id == 2 and message == "Hello from pc2" then
[[write]]("PC2 -")
[[print]](message)
[[Rednet_(API)|rednet]].[[Rednet.send|send]](2,"How are you") --Send a message only to the PC with ID 2
[[print]]("PC1 - How are you")
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]](10) --Wait until a message arrives or 10 seconds pass
if message == "Fine thanks" then
[[print]]("PC2 - Fine thanks")
end
end
[[print]]("disconnecting")
[[Rednet_(API)|rednet]].[[Rednet.close|close]]("right") --disable modem on the right side of the PC

PC2
[[Rednet_(API)|rednet]].[[Rednet.open|open]]("right") --enable modem on the right side of the PC
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]]() --wait until a mesage is received
if id == 1 and message == "Hello world" then
[[Rednet_(API)|rednet]].[[Rednet.send|send]](1,"Hello from pc2") -- send a message to only the PC with ID 1
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]]() -- Wait until a message is received
if message == "How are you" then
[[Rednet_(API)|rednet]].[[Rednet.broadcast|broadcast]]("Fine thanks") -- Send to all PCs in range
end
end
[[Rednet_(API)|rednet]].[[Rednet.close|close]]("right") -- disable modem on the right side of the PC

Open PC2 first after that open PC1 and then run the program

[[Category:Tutorials]]

Rednet Tutorial

2015-08-05T19:13:31Z

Randomdude999: Fixed recipe

Rednet is an API that allows computers and turtles interact with each other wirelessly.

== Getting started ==

* Attach a [[Wireless Modem|wireless modem]] to your [[Computer|computer]].
{{Crafting grid
|A1=stone |B1=stone |C1=stone
|A2=stone |B2=ender_pearl |C2=stone
|A3=stone |B3=stone |C3=stone
|Output=Modem
}}

A modem is made using 8 stone blocks surrounding a redstone torch.

== Rednet scripts ==
Rednet uses several methods to interact with other computers.

Here is a basic program that runs most of them. It requires 2 PCs.

PC1
[[Rednet_(API)|rednet]].[[Rednet.open|open]]("right") --enable the modem attached to the right side of the PC
[[Rednet_(API)|rednet]].[[Rednet.broadcast|broadcast]]("Hello world") --send "Hello world" over rednet to all PCs in range
[[print]]("PC1 - Hello world")
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]]() --wait until something is received over rednet
if id == 2 and message == "Hello from pc2" then
[[write]]("PC2 -")
[[print]](message)
[[Rednet_(API)|rednet]].[[Rednet.send|send]](2,"How are you") --Send a message only to the PC with ID 2
[[print]]("PC1 - How are you")
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]](10) --Wait until a message arrives or 10 seconds pass
if message == "Fine thanks" then
[[print]]("PC2 - Fine thanks")
end
end
[[print]]("disconnecting")
[[Rednet_(API)|rednet]].[[Rednet.close|close]]("right") --disable modem on the right side of the PC

PC2
[[Rednet_(API)|rednet]].[[Rednet.open|open]]("right") --enable modem on the right side of the PC
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]]() --wait until a mesage is received
if id == 1 and message == "Hello world" then
[[Rednet_(API)|rednet]].[[Rednet.send|send]](1,"Hello from pc2") -- send a message to only the PC with ID 1
id,message = [[Rednet_(API)|rednet]].[[Rednet.receive|receive]]() -- Wait until a message is received
if message == "How are you" then
[[Rednet_(API)|rednet]].[[Rednet.broadcast|broadcast]]("Fine thanks") -- Send to all PCs in range
end
end
[[Rednet_(API)|rednet]].[[Rednet.close|close]]("right") -- disable modem on the right side of the PC

Open PC2 first after that open PC1 and then run the program

[[Category:Tutorials]]