Difference between revisions of "Io.open"

From GiderosMobile
(redone)
Line 28: Line 28:
 
=== Return values ===
 
=== Return values ===
 
'''Returns''' (file) file object<br/>
 
'''Returns''' (file) file object<br/>
 +
 +
=== Example ===
 +
'''To copy a file'''
 +
<source 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>
  
 
{{Io}}
 
{{Io}}

Revision as of 08:38, 2 July 2022

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.

(file) = io.open(filename, mode)


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

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