Returns the absolute part of its polar form.
Complex(-1).abs #=> 1 Complex(3.0, -4.0).abs #=> 5.0
Returns the value as a string for inspection.
Complex(2).inspect #=> "(2+0i)" Complex('-8/6').inspect #=> "((-4/3)+0i)" Complex('1/2i').inspect #=> "(0+(1/2)*i)" Complex(0, Float::INFINITY).inspect #=> "(0+Infinity*i)" Complex(Float::NAN, Float::NAN).inspect #=> "(NaN+NaN*i)"
Always returns the string “nil”.
Returns zero.
Returns the absolute value of num.
12.abs #=> 12 (-34.56).abs #=> 34.56 -34.56.abs #=> 34.56
Numeric#magnitude is an alias of Numeric#abs.
Returns true if num is an Integer (including Fixnum and Bignum).
(1.0).integer? #=> false (1).integer? #=> true
Inserts other_str before the character at the given index, modifying str. Negative indices count from the end of the string, and insert after the given character. The intent is insert aString so that it starts at the given index.
"abcd".insert(0, 'X') #=> "Xabcd" "abcd".insert(3, 'X') #=> "abcXd" "abcd".insert(4, 'X') #=> "abcdX" "abcd".insert(-3, 'X') #=> "abXcd" "abcd".insert(-1, 'X') #=> "abcdX"
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.
Returns the index of the first occurrence of the given substring or pattern (regexp) in str. Returns nil if not found. If the second parameter is present, it specifies the position in the string to begin the search.
"hello".index('e') #=> 1 "hello".index('lo') #=> 3 "hello".index('a') #=> nil "hello".index(?e) #=> 1 "hello".index(/[aeiou]/, -3) #=> 4
Returns the index of the last occurrence of the given substring or pattern (regexp) in str. Returns nil if not found. If the second parameter is present, it specifies the position in the string to end the search—characters beyond this point will not be considered.
"hello".rindex('e') #=> 1 "hello".rindex('l') #=> 3 "hello".rindex('a') #=> nil "hello".rindex(?e) #=> 1 "hello".rindex(/[aeiou]/, -2) #=> 1
Returns a printable version of str, surrounded by quote marks, with special characters escaped.
str = "hello" str[3] = "\b" str.inspect #=> "\"hel\\bo\""
Returns an array of lines in str split using the supplied record separator ($/ by default). This is a shorthand for str.each_line(separator).to_a.
If a block is given, which is a deprecated form, works the same as each_line.
Returns an array of the Integer ordinals of the characters in str. This is a shorthand for str.each_codepoint.to_a.
If a block is given, which is a deprecated form, works the same as each_codepoint.
Returns the Symbol corresponding to str, creating the symbol if it did not previously exist. See Symbol#id2name.
"Koala".intern #=> :Koala s = 'cat'.to_sym #=> :cat s == :cat #=> true s = '@cat'.to_sym #=> :@cat s == :@cat #=> true
This can also be used to create symbols that cannot be represented using the :xxx notation.
'cat and dog'.to_sym #=> :"cat and dog"
Returns true if str contains the given string or character.
"hello".include? "lo" #=> true "hello".include? "ol" #=> false "hello".include? ?h #=> true
Returns the Encoding object that represents the encoding of obj.
Returns true if float is a valid IEEE floating point number (it is not infinite, and Float#nan? is false).
Returns a string containing a representation of self. As well as a fixed or exponential form of the float, the call may return NaN, Infinity, and -Infinity.
Return a string describing this Dir object.
Repositions dir to the first entry.
d = Dir.new("testdir") d.read #=> "." d.rewind #=> #<Dir:0x401b3fb0> d.read #=> "."
Deletes the named directory. Raises a subclass of SystemCallError if the directory isn’t empty.
Creates a new name for an existing file using a hard link. Will not overwrite new_name if it already exists (raising a subclass of SystemCallError). Not available on all platforms.
File.link("testfile", ".testfile") #=> 0 IO.readlines(".testfile")[0] #=> "This is line one\n"
Creates a symbolic link called new_name for the existing file old_name. Raises a NotImplemented exception on platforms that do not support symbolic links.
File.symlink("testfile", "link2test") #=> 0
Returns the name of the file referenced by the given link. Not available on all platforms.
File.symlink("testfile", "link2test") #=> 0 File.readlink("link2test") #=> "testfile"