Opens the file, optionally seeks to the given offset, writes string, then returns the length written. write ensures the file is closed before returning. If offset is not given in write mode, the file is truncated. Otherwise, it is not truncated.
If the last argument is a hash, it specifies option for internal open(). The key would be the following. open_args: is exclusive to others.
encoding: string or encoding
specifies encoding of the read string. encoding will be ignored
if length is specified.
mode: string
specifies mode argument for open(). it should start with "w" or "a" or "r+"
otherwise it would cause error.
perm: fixnum
specifies perm argument for open().
open_args: array
specifies arguments for open() as an array.
IO.write("testfile", "0123456789", 20) # => 10
# File could contain: "This is line one\nThi0123456789two\nThis is line three\nAnd so on...\n"
IO.write("testfile", "0123456789") #=> 10
# File would now read: "0123456789"
This is a deprecated alias for each_line.
This is a deprecated alias for each_codepoint.
Writes the given string to ios using a low-level write. Returns the number of bytes written. Do not mix with other methods that write to ios or you may get unpredictable results. Raises SystemCallError on error.
f = File.new("out", "w") f.syswrite("ABCDEF") #=> 6
Returns the current line number in ios. The stream must be opened for reading. lineno counts the number of times gets is called rather than the number of newlines encountered. The two values will differ if gets is called with a separator other than newline.
Methods that use $/ like each, lines and readline will also increment lineno.
See also the $. variable.
f = File.new("testfile") f.lineno #=> 0 f.gets #=> "This is line one\n" f.lineno #=> 1 f.gets #=> "This is line two\n" f.lineno #=> 2
Manually sets the current line number to the given value. $. is updated only on the next read.
f = File.new("testfile") f.gets #=> "This is line one\n" $. #=> 1 f.lineno = 1000 f.lineno #=> 1000 $. #=> 1 # lineno of last read f.gets #=> "This is line two\n" $. #=> 1001 # lineno of last read
Reads all of the lines in ios, and returns them in anArray. Lines are separated by the optional sep. If sep is nil, the rest of the stream is returned as a single record. If the first argument is an integer, or optional second argument is given, the returning string would not be longer than the given value in bytes. The stream must be opened for reading or an IOError will be raised.
f = File.new("testfile") f.readlines[0] #=> "This is line one\n"
Writes the given string to ios. The stream must be opened for writing. If the argument is not a string, it will be converted to a string using to_s. Returns the number of bytes written.
count = $stdout.write("This is a test\n") puts "That was #{count} bytes of data"
produces:
This is a test That was 15 bytes of data
Reads a line as with IO#gets, but raises an EOFError on end of file.
Pushes back bytes (passed as a parameter) onto ios, such that a subsequent buffered read will return it. Only one byte may be pushed back before a subsequent read operation (that is, you will be able to read only the last of several bytes that have been pushed back). Has no effect with unbuffered reads (such as IO#sysread).
f = File.new("testfile") #=> #<File:testfile> b = f.getbyte #=> 0x38 f.ungetbyte(b) #=> nil f.getbyte #=> 0x38
Pushes back one character (passed as a parameter) onto ios, such that a subsequent buffered character read will return it. Only one character may be pushed back before a subsequent read operation (that is, you will be able to read only the last of several characters that have been pushed back). Has no effect with unbuffered reads (such as IO#sysread).
f = File.new("testfile") #=> #<File:testfile> c = f.getc #=> "8" f.ungetc(c) #=> nil f.getc #=> "8"
Positions ios to the beginning of input, resetting lineno to zero.
f = File.new("testfile") f.readline #=> "This is line one\n" f.rewind #=> 0 f.lineno #=> 0 f.readline #=> "This is line one\n"
Note that it cannot be used with streams such as pipes, ttys, and sockets.
Puts ios into binary mode. Once a stream is in binary mode, it cannot be reset to nonbinary mode.
newline conversion disabled
encoding conversion disabled
content is treated as ASCII-8BIT
Returns true if ios is binmode.
Return a string describing this IO object.
Associates the value value with the specified key.
Returns the number of key-value pairs in this database.
Returns a hash created by using gdbm’s values as keys, and the keys as values.
Turns the database’s fast mode on or off. If fast mode is turned on, gdbm does not wait for writes to be flushed to the disk before continuing.
This option is obsolete for gdbm >= 1.8 since fast mode is turned on by default. See also: syncmode=
Returns true if the given key k exists within the database. Returns false otherwise.
Iterates over the range, passing each nth element to the block. If begin and end are numeric, n is added for each iteration. Otherwise step invokes succ to iterate through range elements.
If no block is given, an enumerator is returned instead.
range = Xs.new(1)..Xs.new(10) range.step(2) {|x| puts x} puts range.step(3) {|x| puts x}
produces:
1 x 3 xxx 5 xxxxx 7 xxxxxxx 9 xxxxxxxxx 1 x 4 xxxx 7 xxxxxxx 10 xxxxxxxxxx
See Range for the definition of class Xs.
Returns the first object in the range, or an array of the first n elements.
(10..20).first #=> 10 (10..20).first(3) #=> [10, 11, 12]
Returns the last object in the range, or an array of the last n elements.
Note that with no arguments last will return the object that defines the end of the range even if exclude_end? is true.
(10..20).last #=> 20 (10...20).last #=> 20 (10..20).last(3) #=> [18, 19, 20] (10...20).last(3) #=> [17, 18, 19]
Returns the minimum value in the range. Returns nil if the begin value of the range is larger than the end value.
Can be given an optional block to override the default comparison method a <=> b.
(10..20).min #=> 10