Io.open

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

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• Io
• Io.close
• Io.flush
• Io.input
• Io.lines
• Io.open
• Io.output
• Io.read
• Io.tmpfile
• Io.type
• Io.write

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