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how to create an array with range values
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Date created
Mar 1, 2020
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Section 1
(50 cards)
how to create an array with range values
alpha = 'a'..'z' alpha_arr = [*alpha]
how to get the last value of an array
arr[-1] or arr[arr.length -1]
Ternary operator is used in ruby also
puts nil == nil ? "Yes it is": "no it is not"
What are the two types of ranges
Inclusive range 1..5 = 1.2.3.4.5 Exclusive range 1...5 = 1.2.3.4
how to append an array with a value at last
array = [] array << 4 OR array[array.length - 1] = 4
method to get absolute value
-2.abs
how to use unless
it like negation of if unless array.empty?
how to write IF blook
if (nil == nil) elsif boolean else end check how elsif is written
how to get the object id
obj.object_id
which method is used to increment a integer value
.NEXT 457.next
Ho to reverse an array
arr.reverse
how to reverse an array in place
With a BANG after .reverse arr.reverse!
x = y || z what does this mean
Short hand for writing this is if y x = y else x = z
remove nil from array
arr.compact arr.compact!
write a while and until loop
while boolean end ---------- until boolean end
method to round a float
round floor - this will round to lowest value ceil - this will round to ceiling number which is the greatest
Find if something is nil
product.nil? product == nil !product
write a basic loop
loop do end can use below inside a loop redo - redo this loop next - jump to next loop break - terminate the whole loop retry - start over the whole loop
what does this short hand do x ||= y
if X has a value then nothings happens, else y is assigned unless x x = y end
If a array position is empty what will it return
nil
list iterators with hash class
each_key each_value each_pair
how many iterators are there and list them
Total four 5.times {puts "hello"} 1.upto(5) { puts "Hello" } 5.downto(1) {puts "hello"} (1..5).each { puts "hello" }
Interpolation
#{} msg = 'I love you' puts "I want to say that #{msg}"
how to declare an array
Arrays don't care about the object types x = [1,2,3,4,5,'axczxc', nil]
find the length of a string
"swer".length 4
string escaping
'Let\'s escape'
array delete a value
arr.delete('3')
Get all the keys in a hash
car.keys
how to join values in a array
arr.join arr.join(",")
how to write a case statement
case when boolean when boolean end OR case count when 0 puts "nobody" when 1 puts "only one" end
Check if an array has an element
arr.include?('venkat')
array delete a value at a position
arr.delete_at(4)
Symbols are like a strings but cant be edited begins with column
:first_name :pi_value person = { :first_name => 'venky', :last_name => 'tad' }
how to make uppercase with string
"str".upcase
list iterators in string class
each_line each_char each_byte
List the iterators in numbers class
times, upto, downto, step
which integer method is used to convert an int to float and vice versa
100.to_f 10.3.to_i
how to shuffel an array
arr.shuffle arr.
check if an array is empty
[].empty?
check if a hash has key and value
hash.has_key?('fname') hash.has_value('lname')
what is the convention to declare a constant
MAX_SCORE = 100 Ruby still allows to over write and gives a warning Constants can also be started with capital letter Person
remove duplicates in an array
arr.uniq arr.uniq!
how to flatten contents of array by
[1,2, [3, 4], 5, 6].flatten [1,2,3,4,5,6]
list iterators with array class
EACH, each_index, each_with_index
To expect a result in float, what is a pre-requisite
Atleast one number should be float 10/3 = 3 10.0/3 = 3.333335
convert a hash to array
hash.to_a
how to use downto iterator
5.downto(1) do |G| puts "countdown -- #{G}" end
list iterators by range
each, step
Whats spacility in hash
we can relay on position they are object indexed instead of position indexed like arrays It's like key value pair car = { 'brand' => 'ford', 'model' => 'mustand' 'color' => 'blue', 'interier_color' => 'tan' } car['brand'] car['price'] = '29,403'
what does find do ?
(1..10).find {|n| n == 5 } It returns the matched condition
Section 2
(11 cards)