Return true if this array is frozen (or temporarily frozen while being sorted). See also Object#frozen?
Returns a new array by rotating self so that the element at count is the first element of the new array.
If count is negative then it rotates in the opposite direction, starting from the end of self where -1 is the last element.
a = [ "a", "b", "c", "d" ] a.rotate #=> ["b", "c", "d", "a"] a #=> ["a", "b", "c", "d"] a.rotate(2) #=> ["c", "d", "a", "b"] a.rotate(-3) #=> ["b", "c", "d", "a"]
Rotates self in place so that the element at count comes first, and returns self.
If count is negative then it rotates in the opposite direction, starting from the end of the array where -1 is the last element.
a = [ "a", "b", "c", "d" ] a.rotate! #=> ["b", "c", "d", "a"] a #=> ["b", "c", "d", "a"] a.rotate!(2) #=> ["d", "a", "b", "c"] a.rotate!(-3) #=> ["a", "b", "c", "d"]
Searches through an array whose elements are also arrays comparing obj with the first element of each contained array using obj.==.
Returns the first contained array that matches (that is, the first associated array), or nil if no match is found.
See also Array#rassoc
s1 = [ "colors", "red", "blue", "green" ] s2 = [ "letters", "a", "b", "c" ] s3 = "foo" a = [ s1, s2, s3 ] a.assoc("letters") #=> [ "letters", "a", "b", "c" ] a.assoc("foo") #=> nil
Searches through the array whose elements are also arrays.
Compares obj with the second element of each contained array using obj.==.
Returns the first contained array that matches obj.
See also Array#assoc.
a = [ [ 1, "one"], [2, "two"], [3, "three"], ["ii", "two"] ] a.rassoc("two") #=> [2, "two"] a.rassoc("four") #=> nil
Drops first n elements from ary and returns the rest of the elements in an array.
If a negative number is given, raises an ArgumentError.
See also Array#take
a = [1, 2, 3, 4, 5, 0] a.drop(3) #=> [4, 5, 0]
Returns the freeze status of obj.
a = [ "a", "b", "c" ] a.freeze #=> ["a", "b", "c"] a.frozen? #=> true
Returns true if self is a prime number, else returns false.
Rounds int to a given precision in decimal digits (default 0 digits).
Precision may be negative. Returns a floating point number when ndigits is positive, self for zero, and round down for negative.
1.round #=> 1 1.round(2) #=> 1.0 15.round(-1) #=> 20
Returns true if num has a zero value.
Returns self if num is not zero, nil otherwise.
This behavior is useful when chaining comparisons:
a = %w( z Bb bB bb BB a aA Aa AA A ) b = a.sort {|a,b| (a.downcase <=> b.downcase).nonzero? || a <=> b } b #=> ["A", "a", "AA", "Aa", "aA", "BB", "Bb", "bB", "bb", "z"]
Rounds num to a given precision in decimal digits (default 0 digits).
Precision may be negative. Returns a floating point number when ndigits is more than zero.
Numeric implements this by converting itself to a Float and invoking Float#round.
Treats leading characters of str as a string of octal digits (with an optional sign) and returns the corresponding number. Returns 0 if the conversion fails.
"123".oct #=> 83 "-377".oct #=> -255 "bad".oct #=> 0 "0377bad".oct #=> 255
If str starts with 0, radix indicators are honored. See Kernel#Integer.
Prepend—Prepend the given strings to str.
a = "!" a.prepend("hello ", "world") #=> "hello world!" a #=> "hello world!"
See also String#concat.
Returns true if float is 0.0.
Rounds float to a given precision in decimal digits (default 0 digits).
Precision may be negative. Returns a floating point number when ndigits is more than zero.
1.4.round #=> 1 1.5.round #=> 2 1.6.round #=> 2 (-1.5).round #=> -2 1.234567.round(2) #=> 1.23 1.234567.round(3) #=> 1.235 1.234567.round(4) #=> 1.2346 1.234567.round(5) #=> 1.23457 34567.89.round(-5) #=> 0 34567.89.round(-4) #=> 30000 34567.89.round(-3) #=> 35000 34567.89.round(-2) #=> 34600 34567.89.round(-1) #=> 34570 34567.89.round(0) #=> 34568 34567.89.round(1) #=> 34567.9 34567.89.round(2) #=> 34567.89 34567.89.round(3) #=> 34567.89
If half: optional keyword is given, just-half number will be rounded according to that value. Supported values for this keyword are follows.
:up or nil: the result will be rounded away from zero
:even: the result will be rounded to nearest even number
:down: the result will be rounded close to zero
Changes this process’s idea of the file system root. Only a privileged process may make this call. Not available on all platforms. On Unix systems, see chroot(2) for more information.
Locks or unlocks a file according to locking_constant (a logical or of the values in the table below). Returns false if File::LOCK_NB is specified and the operation would otherwise have blocked. Not available on all platforms.
Locking constants (in class File):
LOCK_EX | Exclusive lock. Only one process may hold an
| exclusive lock for a given file at a time.
----------+------------------------------------------------
LOCK_NB | Don't block when locking. May be combined
| with other lock options using logical or.
----------+------------------------------------------------
LOCK_SH | Shared lock. Multiple processes may each hold a
| shared lock for a given file at the same time.
----------+------------------------------------------------
LOCK_UN | Unlock.
Example:
# update a counter using write lock # don't use "w" because it truncates the file before lock. File.open("counter", File::RDWR|File::CREAT, 0644) {|f| f.flock(File::LOCK_EX) value = f.read.to_i + 1 f.rewind f.write("#{value}\n") f.flush f.truncate(f.pos) } # read the counter using read lock File.open("counter", "r") {|f| f.flock(File::LOCK_SH) p f.read }
Returns true if the named file exists and has a zero size.
file_name can be an IO object.
Invokes Module.prepend_features on each parameter in reverse order.