Ruby/Array/Two Array Indices
Материал из Wiki.crossplatform.ru
array[1, 2] references two array elements, starting with the element at index 1, and this statement replaces two elements in the array, not just one:
array = ["Hello", "there", "AAA", 1, 2, 3] array[1, 2] = "here" p array
Assigning a value to array[3, 0] did not replace any element in the array; it inserted a new element starting at index 3 instead.
array = ["Hello", "there", "AAA", 1, 2, 3] array[3, 0] = "pie" puts array
In Ruby the first index is the start location and the second holds the count: array[start, count].
array = ["Hello", "there", "AAA", 1, 2, 3] array[1] = "here" p array array = ["Hello", "there", "AAA", 1, 2, 3] array[1, 1] = "here" p array
Instead of [], you can also use the slice method, another alias
year = [2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009] year.slice(1) # => 2001 year.slice(0,4) # => [2000, 2001, 2002, 2003] year.slice(0..2) # => [2000, 2001, 2002] year.slice(0...2) # => [2000, 2001]
specify where to start in the array and how many elements you want
year = [2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009] year[0, 3] # => [2000, 2001, 2002] # The 0 is the start parameter. It says to start at 0, or the beginning of the array. # The second is the length parameter, which tells how many elements you want.
use a range:
year = [2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009] year[7..9] # => [2007, 2008, 2009] #two dots means "include both elements," and three dots means "don"t include the last element."
Using Two Array Indices
array = ["Hello", "there", "AAA", 1, 2, 3] array[2, 1] = "pal" p array array = ["Hello", "there", "AAA", 1, 2, 3] array[3, 0] = "pie" p array array = ["Now", "is", 1, 2, 3] array[2, 0] = ["the", "time"] p array array = ["Hello", "there", "AAA", 1, 2, 3] array2 = array[3, 3] p array2
