Tries to return the element at position index, but throws an IndexError exception if the referenced index lies outside of the array bounds. This error can be prevented by supplying a second argument, which will act as a default value.
Alternatively, if a block is given it will only be executed when an invalid index is referenced.
Negative values of index count from the end of the array.
a = [ 11, 22, 33, 44 ] a.fetch(1) #=> 22 a.fetch(-1) #=> 44 a.fetch(4, 'cat') #=> "cat" a.fetch(100) { |i| puts "#{i} is out of bounds" } #=> "100 is out of bounds"
Calls the given block once for each element in self, passing that element as a parameter. Returns the array itself.
If no block is given, an Enumerator is returned.
a = [ "a", "b", "c" ] a.each {|x| print x, " -- " }
produces:
a -- b -- c --
By using binary search, finds a value from this array which meets the given condition in O(log n) where n is the size of the array.
You can use this method in two use cases: a find-minimum mode and a find-any mode. In either case, the elements of the array must be monotone (or sorted) with respect to the block.
In find-minimum mode (this is a good choice for typical use case), the block must return true or false, and there must be an index i (0 <= i <= ary.size) so that:
the block returns false for any element whose index is less than i, and
the block returns true for any element whose index is greater than or equal to i.
This method returns the i-th element. If i is equal to ary.size, it returns nil.
ary = [0, 4, 7, 10, 12] ary.bsearch {|x| x >= 4 } #=> 4 ary.bsearch {|x| x >= 6 } #=> 7 ary.bsearch {|x| x >= -1 } #=> 0 ary.bsearch {|x| x >= 100 } #=> nil
In find-any mode (this behaves like libc’s bsearch(3)), the block must return a number, and there must be two indices i and j (0 <= i <= j <= ary.size) so that:
the block returns a positive number for ary if 0 <= k < i,
the block returns zero for ary if i <= k < j, and
the block returns a negative number for ary if j <= k < ary.size.
Under this condition, this method returns any element whose index is within i…j. If i is equal to j (i.e., there is no element that satisfies the block), this method returns nil.
ary = [0, 4, 7, 10, 12] # try to find v such that 4 <= v < 8 ary.bsearch {|x| 1 - x / 4 } #=> 4 or 7 # try to find v such that 8 <= v < 10 ary.bsearch {|x| 4 - x / 2 } #=> nil
You must not mix the two modes at a time; the block must always return either true/false, or always return a number. It is undefined which value is actually picked up at each iteration.
Returns a string containing the character represented by the int‘s value according to encoding.
65.chr #=> "A" 230.chr #=> "\346" 255.chr(Encoding::UTF_8) #=> "\303\277"
Converts pattern to a Regexp (if it isn’t already one), then invokes its match method on str. If the second parameter is present, it specifies the position in the string to begin the search.
'hello'.match('(.)\1') #=> #<MatchData "ll" 1:"l"> 'hello'.match('(.)\1')[0] #=> "ll" 'hello'.match(/(.)\1/)[0] #=> "ll" 'hello'.match('xx') #=> nil
If a block is given, invoke the block with MatchData if match succeed, so that you can write
str.match(pat) {|m| ...}
instead of
if m = str.match(pat) ... end
The return value is a value from block execution in this case.
Converts pattern to a Regexp (if it isn’t already one), then returns a true or false indicates whether the regexp is matched str or not without updating $~ and other related variables. If the second parameter is present, it specifies the position in the string to begin the search.
"Ruby".match?(/R.../) #=> true "Ruby".match?(/R.../, 1) #=> false "Ruby".match?(/P.../) #=> false $& #=> nil
Returns an array of characters in str. This is a shorthand for str.each_char.to_a.
If a block is given, which is a deprecated form, works the same as each_char.
Returns a new String with the last character removed. If the string ends with \r\n, both characters are removed. Applying chop to an empty string returns an empty string. String#chomp is often a safer alternative, as it leaves the string unchanged if it doesn’t end in a record separator.
"string\r\n".chop #=> "string" "string\n\r".chop #=> "string\n" "string\n".chop #=> "string" "string".chop #=> "strin" "x".chop.chop #=> ""
Returns a new String with the given record separator removed from the end of str (if present). If $/ has not been changed from the default Ruby record separator, then chomp also removes carriage return characters (that is it will remove \n, \r, and \r\n). If $/ is an empty string, it will remove all trailing newlines from the string.
"hello".chomp #=> "hello" "hello\n".chomp #=> "hello" "hello\r\n".chomp #=> "hello" "hello\n\r".chomp #=> "hello\n" "hello\r".chomp #=> "hello" "hello \n there".chomp #=> "hello \n there" "hello".chomp("llo") #=> "he" "hello\r\n\r\n".chomp('') #=> "hello" "hello\r\n\r\r\n".chomp('') #=> "hello\r\n\r"
Processes str as for String#chop, returning str, or nil if str is the empty string. See also String#chomp!.
Modifies str in place as described for String#chomp, returning str, or nil if no modifications were made.
Returns true if path matches against pattern. The pattern is not a regular expression; instead it follows rules similar to shell filename globbing. It may contain the following metacharacters:
*
Matches any file. Can be restricted by other values in the glob. Equivalent to / .* /x in regexp.
*
Matches all files regular files
c*
Matches all files beginning with c
*c
Matches all files ending with c
*c*
Matches all files that have c in them (including at the beginning or end).
To match hidden files (that start with a . set the File::FNM_DOTMATCH flag.
**
Matches directories recursively or files expansively.
?
Matches any one character. Equivalent to /.{1}/ in regexp.
[set]
Matches any one character in set. Behaves exactly like character sets in Regexp, including set negation ([^a-z]).
\
Escapes the next metacharacter.
{a,b}
Matches pattern a and pattern b if File::FNM_EXTGLOB flag is enabled. Behaves like a Regexp union ((?:a|b)).
flags is a bitwise OR of the FNM_XXX constants. The same glob pattern and flags are used by Dir::glob.
Examples:
File.fnmatch('cat', 'cat') #=> true # match entire string File.fnmatch('cat', 'category') #=> false # only match partial string File.fnmatch('c{at,ub}s', 'cats') #=> false # { } isn't supported by default File.fnmatch('c{at,ub}s', 'cats', File::FNM_EXTGLOB) #=> true # { } is supported on FNM_EXTGLOB File.fnmatch('c?t', 'cat') #=> true # '?' match only 1 character File.fnmatch('c??t', 'cat') #=> false # ditto File.fnmatch('c*', 'cats') #=> true # '*' match 0 or more characters File.fnmatch('c*t', 'c/a/b/t') #=> true # ditto File.fnmatch('ca[a-z]', 'cat') #=> true # inclusive bracket expression File.fnmatch('ca[^t]', 'cat') #=> false # exclusive bracket expression ('^' or '!') File.fnmatch('cat', 'CAT') #=> false # case sensitive File.fnmatch('cat', 'CAT', File::FNM_CASEFOLD) #=> true # case insensitive File.fnmatch('?', '/', File::FNM_PATHNAME) #=> false # wildcard doesn't match '/' on FNM_PATHNAME File.fnmatch('*', '/', File::FNM_PATHNAME) #=> false # ditto File.fnmatch('[/]', '/', File::FNM_PATHNAME) #=> false # ditto File.fnmatch('\?', '?') #=> true # escaped wildcard becomes ordinary File.fnmatch('\a', 'a') #=> true # escaped ordinary remains ordinary File.fnmatch('\a', '\a', File::FNM_NOESCAPE) #=> true # FNM_NOESCAPE makes '\' ordinary File.fnmatch('[\?]', '?') #=> true # can escape inside bracket expression File.fnmatch('*', '.profile') #=> false # wildcard doesn't match leading File.fnmatch('*', '.profile', File::FNM_DOTMATCH) #=> true # period by default. File.fnmatch('.*', '.profile') #=> true rbfiles = '**' '/' '*.rb' # you don't have to do like this. just write in single string. File.fnmatch(rbfiles, 'main.rb') #=> false File.fnmatch(rbfiles, './main.rb') #=> false File.fnmatch(rbfiles, 'lib/song.rb') #=> true File.fnmatch('**.rb', 'main.rb') #=> true File.fnmatch('**.rb', './main.rb') #=> false File.fnmatch('**.rb', 'lib/song.rb') #=> true File.fnmatch('*', 'dave/.profile') #=> true pattern = '*' '/' '*' File.fnmatch(pattern, 'dave/.profile', File::FNM_PATHNAME) #=> false File.fnmatch(pattern, 'dave/.profile', File::FNM_PATHNAME | File::FNM_DOTMATCH) #=> true pattern = '**' '/' 'foo' File.fnmatch(pattern, 'a/b/c/foo', File::FNM_PATHNAME) #=> true File.fnmatch(pattern, '/a/b/c/foo', File::FNM_PATHNAME) #=> true File.fnmatch(pattern, 'c:/a/b/c/foo', File::FNM_PATHNAME) #=> true File.fnmatch(pattern, 'a/.b/c/foo', File::FNM_PATHNAME) #=> false File.fnmatch(pattern, 'a/.b/c/foo', File::FNM_PATHNAME | File::FNM_DOTMATCH) #=> true
Returns true if path matches against pattern. The pattern is not a regular expression; instead it follows rules similar to shell filename globbing. It may contain the following metacharacters:
*
Matches any file. Can be restricted by other values in the glob. Equivalent to / .* /x in regexp.
*
Matches all files regular files
c*
Matches all files beginning with c
*c
Matches all files ending with c
*c*
Matches all files that have c in them (including at the beginning or end).
To match hidden files (that start with a . set the File::FNM_DOTMATCH flag.
**
Matches directories recursively or files expansively.
?
Matches any one character. Equivalent to /.{1}/ in regexp.
[set]
Matches any one character in set. Behaves exactly like character sets in Regexp, including set negation ([^a-z]).
\
Escapes the next metacharacter.
{a,b}
Matches pattern a and pattern b if File::FNM_EXTGLOB flag is enabled. Behaves like a Regexp union ((?:a|b)).
flags is a bitwise OR of the FNM_XXX constants. The same glob pattern and flags are used by Dir::glob.
Examples:
File.fnmatch('cat', 'cat') #=> true # match entire string File.fnmatch('cat', 'category') #=> false # only match partial string File.fnmatch('c{at,ub}s', 'cats') #=> false # { } isn't supported by default File.fnmatch('c{at,ub}s', 'cats', File::FNM_EXTGLOB) #=> true # { } is supported on FNM_EXTGLOB File.fnmatch('c?t', 'cat') #=> true # '?' match only 1 character File.fnmatch('c??t', 'cat') #=> false # ditto File.fnmatch('c*', 'cats') #=> true # '*' match 0 or more characters File.fnmatch('c*t', 'c/a/b/t') #=> true # ditto File.fnmatch('ca[a-z]', 'cat') #=> true # inclusive bracket expression File.fnmatch('ca[^t]', 'cat') #=> false # exclusive bracket expression ('^' or '!') File.fnmatch('cat', 'CAT') #=> false # case sensitive File.fnmatch('cat', 'CAT', File::FNM_CASEFOLD) #=> true # case insensitive File.fnmatch('?', '/', File::FNM_PATHNAME) #=> false # wildcard doesn't match '/' on FNM_PATHNAME File.fnmatch('*', '/', File::FNM_PATHNAME) #=> false # ditto File.fnmatch('[/]', '/', File::FNM_PATHNAME) #=> false # ditto File.fnmatch('\?', '?') #=> true # escaped wildcard becomes ordinary File.fnmatch('\a', 'a') #=> true # escaped ordinary remains ordinary File.fnmatch('\a', '\a', File::FNM_NOESCAPE) #=> true # FNM_NOESCAPE makes '\' ordinary File.fnmatch('[\?]', '?') #=> true # can escape inside bracket expression File.fnmatch('*', '.profile') #=> false # wildcard doesn't match leading File.fnmatch('*', '.profile', File::FNM_DOTMATCH) #=> true # period by default. File.fnmatch('.*', '.profile') #=> true rbfiles = '**' '/' '*.rb' # you don't have to do like this. just write in single string. File.fnmatch(rbfiles, 'main.rb') #=> false File.fnmatch(rbfiles, './main.rb') #=> false File.fnmatch(rbfiles, 'lib/song.rb') #=> true File.fnmatch('**.rb', 'main.rb') #=> true File.fnmatch('**.rb', './main.rb') #=> false File.fnmatch('**.rb', 'lib/song.rb') #=> true File.fnmatch('*', 'dave/.profile') #=> true pattern = '*' '/' '*' File.fnmatch(pattern, 'dave/.profile', File::FNM_PATHNAME) #=> false File.fnmatch(pattern, 'dave/.profile', File::FNM_PATHNAME | File::FNM_DOTMATCH) #=> true pattern = '**' '/' 'foo' File.fnmatch(pattern, 'a/b/c/foo', File::FNM_PATHNAME) #=> true File.fnmatch(pattern, '/a/b/c/foo', File::FNM_PATHNAME) #=> true File.fnmatch(pattern, 'c:/a/b/c/foo', File::FNM_PATHNAME) #=> true File.fnmatch(pattern, 'a/.b/c/foo', File::FNM_PATHNAME) #=> false File.fnmatch(pattern, 'a/.b/c/foo', File::FNM_PATHNAME | File::FNM_DOTMATCH) #=> true
Changes permission bits on the named file(s) to the bit pattern represented by mode_int. Actual effects are operating system dependent (see the beginning of this section). On Unix systems, see chmod(2) for details. Returns the number of files processed.
File.chmod(0644, "testfile", "out") #=> 2
Changes the owner and group of the named file(s) to the given numeric owner and group id’s. Only a process with superuser privileges may change the owner of a file. The current owner of a file may change the file’s group to any group to which the owner belongs. A nil or -1 owner or group id is ignored. Returns the number of files processed.
File.chown(nil, 100, "testfile")
Equivalent to File::chmod, but does not follow symbolic links (so it will change the permissions associated with the link, not the file referenced by the link). Often not available.
Equivalent to File::chown, but does not follow symbolic links (so it will change the owner associated with the link, not the file referenced by the link). Often not available. Returns number of files in the argument list.
Changes permission bits on file to the bit pattern represented by mode_int. Actual effects are platform dependent; on Unix systems, see chmod(2) for details. Follows symbolic links. Also see File#lchmod.
f = File.new("out", "w"); f.chmod(0644) #=> 0
Changes the owner and group of file to the given numeric owner and group id’s. Only a process with superuser privileges may change the owner of a file. The current owner of a file may change the file’s group to any group to which the owner belongs. A nil or -1 owner or group id is ignored. Follows symbolic links. See also File#lchown.
File.new("testfile").chown(502, 1000)
Iterates over the block according to how this Enumerator was constructed. If no block and no arguments are given, returns self.
"Hello, world!".scan(/\w+/) #=> ["Hello", "world"] "Hello, world!".to_enum(:scan, /\w+/).to_a #=> ["Hello", "world"] "Hello, world!".to_enum(:scan).each(/\w+/).to_a #=> ["Hello", "world"] obj = Object.new def obj.each_arg(a, b=:b, *rest) yield a yield b yield rest :method_returned end enum = obj.to_enum :each_arg, :a, :x enum.each.to_a #=> [:a, :x, []] enum.each.equal?(enum) #=> true enum.each { |elm| elm } #=> :method_returned enum.each(:y, :z).to_a #=> [:a, :x, [:y, :z]] enum.each(:y, :z).equal?(enum) #=> false enum.each(:y, :z) { |elm| elm } #=> :method_returned
Returns a hash of parsed elements.
Creates a new Date object by parsing from a string according to some typical XML Schema formats.
Date.xmlschema('2001-02-03') #=> #<Date: 2001-02-03 ...>
This method is equivalent to strftime(‘%F’).