Difference between revisions of "Io.open"
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=== Description === | === Description === | ||
This function opens a file in the specified mode. The function returns a new file handle, or nil plus an error message. | This function opens a file in the specified mode. The function returns a new file handle, or nil plus an error message. | ||
| − | < | + | <syntaxhighlight lang="lua"> |
(file) = io.open(filename, mode) | (file) = io.open(filename, mode) | ||
</source> | </source> | ||
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=== Example === | === Example === | ||
'''To copy a file''' | '''To copy a file''' | ||
| − | < | + | <syntaxhighlight lang="lua"> |
local function copy(src, dst) | local function copy(src, dst) | ||
local srcf = io.open(src, "rb") | local srcf = io.open(src, "rb") | ||
Revision as of 15:28, 13 July 2023
Available since: Gideros 2011.6
Class: io
Description
This function opens a file in the specified mode. The function returns a new file handle, or nil plus an error message. <syntaxhighlight lang="lua"> (file) = io.open(filename, mode) </source>
The mode string can be any of the following:
- "r": read mode (the default)
- "w": write mode
- "a": append mode
- "r+": update mode, all previous data is preserved
- "w+": update mode, all previous data is erased
- "a+": append update mode, previous data is preserved, writing is only allowed at the end of file
The mode string can also have a 'b' at the end, which is needed in some systems to open the file in binary mode.
This string is exactly what is used in the standard C function fopen.
Parameters
filename: (string) filename to open
mode: (string) mode in which to open the file optional (default = "r")
Return values
Returns (file) file object
Example
To copy a file <syntaxhighlight lang="lua"> local function copy(src, dst) local srcf = io.open(src, "rb") local dstf = io.open(dst, "wb") local size = 2^13 -- good buffer size (8K) while true do local block = srcf:read(size) if not block then break end dstf:write(block) end srcf:close() dstf:close() end </source>
