My task is to generate a random string with following parameters:
At least one Uppercase
At least one lower
At least one digit
No repeated chars/digits allowed ( e.g. aa not allowed, aba is allowed, Aa is allowed)
I'm able to generate a random string with 1,2,3 parameters but parameter 4 logic is missing.
inputChars = [('a'..'z'), ('A'..'Z'),(0..9)].map(&:to_a).flatten
string = (0...16).map { inputChars[rand(inputChars.length)] }.join
require 'set'
inputChars = [('a'..'z'), ('A'..'Z'),(0..9)].map(&:to_a).flatten
set_string = Set.new
loop do
break if set_string.size == 16
cr = inputChars[rand(inputChars.length)]
set_string << cr
end
output = set_string.to_a.join
i just change your map operation to loop operation and add Set data structure to store the character from random inputChars operation. Using Set will not allow same character
Let's begin by defining two constants.
CHARS_BY_TYPE = {
lower: ('a'..'z').to_a.freeze,
upper: ('A'..'Z').to_a.freeze,
digit: ('0'..'9').to_a.freeze
}.freeze
ALL = (CHARS_BY_TYPE[:lower] + CHARS_BY_TYPE[:upper] + CHARS_BY_TYPE[:digit]).freeze
#=> [["a", "b",..., "z", "A", "B",..., "Z", "0", "1",..., "9"]
I will initially build a string of a specified length by randomly selecting one character at a time from the array ALL, ensuring that no two consecutive characters are the same. There is no assurance, however, that the resulting string will contain at least one uppercase letter, one lowercase letter and one digit.
def append_random_char(last_char)
loop do
ch = ALL.sample
break ch unless ch == last_char
end
end
Our main method will begin as follows:
def random_string(str_len)
raise ArgumentError if str_len < 3
(str_len - 2).times.with_object('') { |_,s| s << append_random_char(s[-1]) }
# ...
end
For example:
s = random_string(40)
#=> "arN64kDw6ClzcNMj8WAkj1NJC2B5oFoRlcXl5S"
str_len is the required string length, 40 in the example. Observe that s contains 38 characters of which no two successive characters are equal. We will need to add 2 characters later. If the string contained no digits, for example, at least one of those two characters added (at a random location) will be a (randomly-selected) digit. If the string were shorter and contained, for example, digits only, the two characters added will be an uppercase letter and a lowercase letter.
Next we need to see if the string is lacking an uppercase letter, a lowercase letter and/or a digit. (It cannot be missing all three, as the string must contain at least three characters.)
require 'set'
def types_to_add(str)
[:lower, :upper, :digit].select do |type|
st = CHARS_BY_TYPE[type].to_set
str.each_char.none? { |ch| st.include?(ch) }
end
end
For the random string generated above we obtain:
types_to_add(s)
#=> []
meaning that the string contains at least one uppercase letter, one lowercase letter and one digit. Try this:
types_to_add(s.gsub(/\d|[A-Z]/, '')
#=> [:upper, :digit]
See Enumerable#none?. CHARS_BY_TYPE[type] is converted to a set merely to speed look-ups.
Suppose now we need to insert an uppercase letter, lowercase letter or digit to satisfy the requirement that there is at least one of each in the string. Specifically, we wish to insert a randomly-drawn character (from CHARS_BY_TYPE[:lower], CHARS_BY_TYPE[:upper] or CHARS_BY_TYPE[:digit]) at a random location in the string we are constructing, with the restriction that neither the preceding nor following character is the same character.
def insert_in_string(str, ch)
i = loop do
i = rand(str.size + 1)
next if ch == str[i]
break i if i.zero? || ch != str[i-1]
end
str.insert(i, ch)
end
For example, if we were to insert the character '0' into (a copy of) our string s (which is not needed):
insert_in_string(s.dup, '0')
#=> "arN64kDw6ClzcN0Mj8WAkj1NJC2B5oFoRlcXl5S"
s #=> "arN64kDw6ClzcNMj8WAkj1NJC2B5oFoRlcXl5S"
^
This inserts the character ch before the character in str at index i. If rand(str.size + 1) returns str.size ch is inserted after the last character of str.
Following this operation the final step is to use the method append_random_char to build the string out to the desired length.
The completed main method is as follows.
def random_string(str_len)
raise ArgumentError if str_len < 3
s = (str_len - 2).times.with_object('') { |_,s| s << append_random_char(s[-1]) }
types_to_add(s).each { |type| insert_in_string(s, CHARS_BY_TYPE[type].sample) }
(str_len - s.size).times { s << append_random_char(s[-1]) }
s
end
s = random_string(40)
#=> "PtQrVFZWUYFwiwRy3ySfAy42G1NT98J6cMVMaWeT"
s.match?(/[a-z]/)
#=> true
s.match?(/[A-Z]/)
#=> true
s.match?(/\d/)
#=> true
s.size
#=> 40
This is how I would do it (warning: Not tested. Just want to present the idea
for my algorithm). I first take a random number for the length of the resulting random string (the length will be between 4 and 16 characters). Then I determine
randomly, how many of them are upper case / lower case / digits, and based on
these decision, I generate the string, ensuring that I don't get any duplicates
in succession.
uchars=('A'..'Z').to_a
lchars=('a'..'z').to_a
dchars=('0'..'9').to_a
charmap = { u: uchars, l: lchars, d: dchars }
total_length=rand(13)+4 # Total length of string to be generated
total_u=rand(total_length-3)+1 # Total number of uchars to be generated
total_l=rand(total_length-total_u-2)+1 # Total number of lchars
total_d=total_length-total_u-total_l # Total number of digits
# Array of types to generate
chartypes=([:u]*total_u + [:l]*total_l + [:d]*total_d).shuffle
# chartypes is an array similar to [:u,:d,:d,:l,:u], where the
# symbols designate the kind of character to be generated.
# outstr : random string to be generated
outstr = charmap[chartypes.first].sample
last_char = outstr.dup
total_length.times do |index|
loop do
nextchar = charmap[chartypes[index]].sample
if nextchar != last_char
outstr << nextchar
last_char = nextchar
break
end
end
end
Trying to add special character (%) sign to variable with following concatenation sign, but it gives me the the error: Invalid characters.
DECLARE Percent CHARACTER CAST ( ' %' AS CHARACTER CCSID 1208);
SET AlocatedAmount = 45
SET InPercent = AlocatedAmount||'%'
Result should be: InPercent = 45%
Error:Invalid characters::45 %
What's going wrong here?
AlocatedAmount seems to be an INTEGER, on what you cannot use the concatenation operator.
You need to cast that to CHARACTER first:
SET InPercent = CAST(AlocatedAmount AS CHARACTER) || '%';
So there is also the option of using FORMAT in your CAST
DECLARE Num INTEGER;
DECLARE FormattedStr CHAR;
SET Num = 45;
SET FormattedStr = CAST(Num AS CHAR FORMAT '#0%');
More information can be found at https://www.ibm.com/support/knowledgecenter/en/SSMKHH_9.0.0/com.ibm.etools.mft.doc/ak05615_.htm
With Ruby, how do I replace a range of characters in a string? For instance, given teh string
hellothere
If I want to replace characters at index positions two through five inclusive with "#" to result in a string
he####here
How would I do this?
You could get a string range and replace it by setting the new character multiplied for the last index plus 1 less the first index:
def replace_in_string(str, replace, start, finish)
str[start..finish] = replace * (finish + 1 - start)
str
end
p replace_in_string 'hellothere', '#', 2, 5
# "he####here"
I need a special Lua pattern that takes all the uppercase letters in a string, and replaces them with a space and the respective lowercase letter;
TestStringOne => test string one
this isA TestString => this is a test string
Can it be done?
Assuming only ASCII is used, this works:
function lowercase(str)
return (str:gsub("%u", function(c) return ' ' .. c:lower() end))
end
print(lowercase("TestStringOne"))
print(lowercase("this isA TestString"))
function my(s)
s = s:gsub('(%S)(%u)', '%1 %2'):lower()
return s
end
print(my('TestStringOne')) -->test string one
print(my('this isA TestString')) -->this is a test string
I checking string for a non-alphanumeric char.
if(str:match("%W")) then
--make str alpha-numeric
end
How to remove all non-alphanumeric chars from string using lua?
Use gsub (as suggested by Egor Skriptunoff):
str = str:gsub('%W','')
just make it like this
you forgot +
if(str:match("%W+")) then --if it contain alpha
number = str:match("%d+")
alpha = str:match("%W+")
end