Returns true if time occurs during Daylight Saving Time in its time zone.
# CST6CDT: Time.local(2000, 1, 1).zone #=> "CST" Time.local(2000, 1, 1).isdst #=> false Time.local(2000, 1, 1).dst? #=> false Time.local(2000, 7, 1).zone #=> "CDT" Time.local(2000, 7, 1).isdst #=> true Time.local(2000, 7, 1).dst? #=> true # Asia/Tokyo: Time.local(2000, 1, 1).zone #=> "JST" Time.local(2000, 1, 1).isdst #=> false Time.local(2000, 1, 1).dst? #=> false Time.local(2000, 7, 1).zone #=> "JST" Time.local(2000, 7, 1).isdst #=> false Time.local(2000, 7, 1).dst? #=> false
Returns true if time occurs during Daylight Saving Time in its time zone.
# CST6CDT: Time.local(2000, 1, 1).zone #=> "CST" Time.local(2000, 1, 1).isdst #=> false Time.local(2000, 1, 1).dst? #=> false Time.local(2000, 7, 1).zone #=> "CDT" Time.local(2000, 7, 1).isdst #=> true Time.local(2000, 7, 1).dst? #=> true # Asia/Tokyo: Time.local(2000, 1, 1).zone #=> "JST" Time.local(2000, 1, 1).isdst #=> false Time.local(2000, 1, 1).dst? #=> false Time.local(2000, 7, 1).zone #=> "JST" Time.local(2000, 7, 1).isdst #=> false Time.local(2000, 7, 1).dst? #=> false
Returns true if time represents Friday.
t = Time.local(1987, 12, 18) #=> 1987-12-18 00:00:00 -0600 t.friday? #=> true
Stores the specified string value in the database, indexed via the string key provided.
Returns the number of entries in the database.
Returns a Hash (not a DBM database) created by using each value in the database as a key, with the corresponding key as its value.
Returns true if the database contains the specified key, false otherwise.
Returns a description of this struct as a string.
Returns the number of struct members.
Customer = Struct.new(:name, :address, :zip) joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345) joe.length #=> 3
Tries to set console size. The effect depends on the platform and the running environment.
You must require ‘io/console’ to use this method.
Returns status information for ios as an object of type File::Stat.
f = File.new("testfile") s = f.stat "%o" % s.mode #=> "100644" s.blksize #=> 4096 s.atime #=> Wed Apr 09 08:53:54 CDT 2003
Reads the entire file specified by name as individual lines, and returns those lines in an array. Lines are separated by sep.
a = IO.readlines("testfile") a[0] #=> "This is line one\n" b = IO.readlines("testfile", chomp: true) b[0] #=> "This is line one"
If the last argument is a hash, it’s the keyword argument to open.
The options hash accepts the following keys:
When the optional chomp keyword argument has a true value, \n, \r, and \r\n will be removed from the end of each line.
See also IO.read for details about open_args.
Opens the file, optionally seeks to the given offset, then returns length bytes (defaulting to the rest of the file). binread ensures the file is closed before returning. The open mode would be "rb:ASCII-8BIT".
IO.binread("testfile") #=> "This is line one\nThis is line two\nThis is line three\nAnd so on...\n" IO.binread("testfile", 20) #=> "This is line one\nThi" IO.binread("testfile", 20, 10) #=> "ne one\nThis is line "
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.
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"
If the last argument is a hash, it specifies options for the internal open(). It accepts the following keys:
string or encoding
Specifies the encoding of the read string. See Encoding.aliases for possible encodings.
string or integer
Specifies the mode argument for open(). It must start with “w”, “a”, or “r+”, otherwise it will cause an error. See IO.new for the list of possible modes.
integer
Specifies the perm argument for open().
array
Specifies arguments for open() as an array. This key can not be used in combination with other keys.
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
Writes the given string to ios at offset using pwrite() system call. This is advantageous to combining IO#seek and IO#write in that it is atomic, allowing multiple threads/process to share the same IO object for reading the file at various locations. This bypasses any userspace buffering of the IO layer. Returns the number of bytes written. Raises SystemCallError on error and NotImplementedError if platform does not implement the system call.
File.open("out", "w") do |f| f.pwrite("ABCDEF", 3) #=> 6 end File.read("out") #=> "\u0000\u0000\u0000ABCDEF"
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 an array. 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 an 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" f = File.new("testfile", chomp: true) f.readlines[0] #=> "This is line one"
See IO.readlines for details about getline_args.
Writes the given strings to ios. The stream must be opened for writing. Arguments that are not a string will be converted to a string using to_s. Returns the number of bytes written in total.
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
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