I am writing a varnish module (VCL) for my backend server. It requires a logic of extracting n characters from a string of undefined length.
I tried regsub() function of vcl with a regex to replace part of the string with empty space.
I need to extract first 20 characters of string. When the string length is 36, i used regex to replace last 16 characters to empty space.
But when length of the string is undefined say 40. i get 24 characters instead of 20. How do i achieve this?
set req.http.mysubstr = regsub(req.http.mystring, ".{16}$", "");
set req.http.mysubstr = regsub(req.http.mystring, ".{($variable)}$", ""); # $variable should be the length of the string - first 20 characters
Use capturing groups:
regsub(req.http.mystring, "^(.{20}).*", "\1")
test it on regex101.com
Related
PurchPackingSlipJournalCreate class -> initHeader method have a line;
vendPackingSlipJour.PackingSlipId = purchParmTable.Num;
but i want when i copy and paste ' FDG 2020 ' (all blanks are tab character) in Num area and click okey, write this value as 'FDG2020' in the PackagingSlipId field of the vendPackingSlipJour table.
I tried -> vendPackingSlipJour.PackingSlipId = strRem(purchParmTable.Num, " ");
but doesn't work for tab character.
How can i remove all whitespace characters from string?
Version 1
Try the strAlpha() function.
From the documentation:
Copies only the alphanumeric characters from a string.
Version 2
Because version 1 also deletes allowed hyphens (-), you could use strKeep().
From the documentation:
Builds a string by using only the characters from the first input string that the second input string specifies should be kept.
This will require you to specify all desired characters, a rather long list...
Version 3
Use regular expressions to replace any unwanted characters (defined as "not a wanted character"). This is similar to version 2, but the list of allowed characters can be expressed a lot shorter.
The example below allows alphanumeric characters(a-z,A-Z,0-9), underscores (_) and hyphens (-). The final value for newText is ABC-12_3.
str badCharacters = #"[^a-zA-Z0-9_-]"; // so NOT an allowed character
str newText = System.Text.RegularExpressions.Regex::Replace(' ABC-12_3 ', badCharacters, '');
Version 4
If you know the only unwanted characters are tabs ('\t'), then you can go hunting for those specifically as well.
vendPackingSlipJour.PackingSlipId = strRem(purchParmTable.Num, '\t');
I have a dropdownlist that has the value of two columns in it... One column is a number ranging from 5 characters long to 8 characters long then a space then the '|' character and another space, followed by a Description for the set of numbers.
An example:
12345678 | Description of Product
In order to pull the items for the dropdownlist into my database I need a to utilize a substring to pull the sequence of numbers out only.
Is it possible to write a substring to pull multiple character lengths? (Sometimes it may be 6 numbers, sometimes 5 numbers, sometimes 8, it would depend on what the user selected from the dropdownlist.)
Use a regular expression for this.
Assuming the number is at the start of the string, you can use the following:
^[0-9]+
Usage:
var theNumbers = RegEx.Match(myDropdownValue, "^[0-9]+").Value;
You could also use string.Split to get the parts separated by | if you know the first part is what you need and will always be numeric:
var theNumbers = myDropdownValue.Split("| ".ToCharArray(),
StringSplitOptions.RemoveEmptyEntries)[0];
Either of these approaches will result in a string. You can use int.Parse on the result in order to get an integer from it.
This is how I would do it
string str = "12345678 | Description of Product";
int delimiter;
delimiter = str.IndexOf("|") - 1;
string ID =str.substring(0, delimiter);
string desc = str.substring(delimiter + 1, str.length - 1);
Try using a regex to pull out the first match of a sequence of numbers of any length. The regex will look something like "^\d+" - starts with any number of decimal digits.
Instead of using substring, you should use Split function.
var words = phrase.Split(new string[] {" | "},
StringSplitOptions.RemoveEmptyEntries);
var number = word[0];
How to convert string to int?I know convert.ToInt32 is used.But it fail.Error is input string is not in proper format.
String s1 = "12.00"
I love the assumption that the decimal separator always is a dot (.). You'd better use the InvariantCulture, which contains a NumberFormat that explicitly specifies the dot as a decimal separator:
Convert.ToInt32(Convert.ToDouble("12.00", CultureInfo.InvariantCulture));
To clarify: half the world uses the dot, the other half a comma. When I run this on a PC with a Dutch culture and do not specify a CultureInfo, it takes the system default (comma) and returns 1200, ignoring the dot.
While it does not directly affect your problem, it is something that can't be stressed enough.
error is because string is "12.00"
first convert string to double than in int
int a = Convert.ToInt32(Convert.ToDouble("12.00"));
or
IF you just want integer part of it than
string s= "12.00";
string[] words = s.Split('.');
int a = Convert.ToInt32(words[0]);
Also check already answered threads on SO : C# Convert String Decimal to Int
"12.00" is a decimal number, not an integer. Integers don't have fractional portions. Use Convert.ToDouble or similar to get a floating-point number, or trim off the decimal part of the string (the . and what follows) prior to calling Convert.ToInt32.
The string "12.00" is a double/decimal value. Use Double.Parse() or Double.TryParse() or Convert.ToDouble().
I need to generate a GUID and save it via a string representation. The string representation should be as short as possible as it will be used as part of an already-long URL string.
Right now, instead of using the normal abcd-efgh-... representation, I use the raw bytes generated and base64-encode them instead, which results in a somewhat shorter string.
But is it possible to make it even shorter?
I'm OK with losing some degree of uniqueness and keeping a counter, but scanning all existing keys is not an option. Suggestions?
I used an Ascii85 encoding for writing a Guid to a database column in 20 ASCII characters. I've posted the C# code in case it is useful. The specific character set may be different for a URL encoding, but you can pick whichever characters suit your application. It's available here: What is the most efficient way to encode an arbitrary GUID into readable ASCII (33-127)?
Sure, just use a base larger than 64. You'll have to encode them using a custom alphabet, but you should be able to find a few more "url-safe" printable ASCII characters.
Base64 encodes 6 bits using 8, so a 16 byte GUID value becomes 22 bytes encoded. You may be able to reduce that by a character or two, but not much more.
I found this discussion interesting: https://www.percona.com/blog/2014/12/19/store-uuid-optimized-way/
Basically you take the 36 characters and turn them into 16 bytes of binary but first sort the three temporal pieces using a stored procedure:
set #uuid:= uuid();
select #uuid;
+--------------------------------------+
| #uuid |
+--------------------------------------+
| 59f3ac1e-06fe-11e6-ac3c-9b18a7fcf9ed |
+--------------------------------------+
CREATE DEFINER=`root`#`localhost`
FUNCTION `ordered_uuid`(uuid BINARY(36))
RETURNS binary(16) DETERMINISTIC
RETURN UNHEX(CONCAT(SUBSTR(uuid, 15, 4),SUBSTR(uuid, 10, 4),SUBSTR(uuid, 1, 8),SUBSTR(uuid, 20, 4),SUBSTR(uuid, 25)));
select hex(ordered_uuid(#uuid));
+----------------------------------+
| hex(ordered_uuid(#uuid)) |
+----------------------------------+
| 11e606fe59f3ac1eac3c9b18a7fcf9ed |
+----------------------------------+
I'm not sure if this is feasible, but you could put all the generated GUIDs in a table and use in the URL only the index of the GUID in the table.
You could also reduce the length of the guid - for example use 2 bytes to indicate the number of days since 2010 for example and 4 bytes for the number of miliseconds since the start of the current day. You will have collisions only for 2 GUIDs generated in the same milisecond. You could also add 2 more random bytes which will make this even better.
(long time, but just came into the same need today)
UUIDs are 128bits long, represented by 32 hex plus 4 hyphens.
If we use a dictionary of 64 (2^6) printable ascii`s, it is just a matter of converting from 32 groups of 4 bits (length of a hex) to 22 groups of 6 bits.
Here is a UUID shortner. Instead 36 chars you get 22, without losing the original bits.
https://gist.github.com/tomlobato/e932818fa7eb989e645f2e64645cf7a5
class UUIDShortner
IGNORE = '-'
BASE6_SLAB = ' ' * 22
# 64 (6 bits) items dictionary
DICT = 'a'.upto('z').to_a +
'A'.upto('Z').to_a +
'0'.upto('9').to_a +
['_', '-']
def self.uuid_to_base6 uuid
uuid_bits = 0
uuid.each_char do |c|
next if c == IGNORE
uuid_bits = (uuid_bits << 4) | c.hex
end
base6 = BASE6_SLAB.dup
base6.size.times { |i|
base6[i] = DICT[uuid_bits & 0b111111]
uuid_bits >>= 6
}
base6
end
end
# Examples:
require 'securerandom'
uuid = ARGV[0] || SecureRandom.uuid
short = UUIDShortner.uuid_to_base6 uuid
puts "#{uuid}\n#{short}"
# ruby uuid_to_base6.rb
# c7e6a9e5-1fc6-4d5a-b889-4734e42b9ecc
# m75kKtZrjIRwnz8hLNQ5hd
You could approach this from the other direction. Produce the shortest possible string representation and map it into a Guid.
Generate the key using a defined alphabet as below:
In psuedocode:
string RandomString(char[] alphabet, int length)
{
StringBuilder result = new StringBuilder();
for (int i = 0; i < length; i++)
result.Append(alphabet[RandomInt(0, alphabet.Length)]);
return result;
}
If you keep the string length < 16, you can simply hex encode the result and pass it to the Guid constructor to parse.
not for exact same problem, but very very close - I have used CRC64, Base64 that and you get 11 bytes, CRC64 has been tested (not proven) to NOT produce duplicates on a wide range of strings.
And since it is 64 bit long by definition - you get the key that is half the size.
To directly answer the original question - you can CRC64 encode any representation of your GUIDs.
Or just run CRC64 on the business key and you will have a 64 bit unique thing that you can then base64.
what's the easiest way to cut string in Flex ?
I mean, I have a sequence of urls, I want them at most 60 characters length. If they are longer they should be cut and "..." should be added at the end.
<mx:LinkButton label="{bookmarksRepeater.currentItem.name}" click="navigateToURL(new URLRequest(event.currentTarget.label.toString()))" />
thanks
if you can run full flex code in the label="" section, perhaps set the label to this:
it's a conditional statement: if the name length is less than or equal to 60, just use the name, otherwise use the first 57 characters of the name and '...'
bookmarksRepeater.currentItem.name.length <= 60 ? bookmarksRepeater.currentItem.name : bookmarksRepeater.currentItem.name.substr(0, 57) + '...'
substr(startIndex:Number = 0, len:Number = 0x7fffffff):String
Returns a substring consisting of the characters that start at the specified startIndex and with a length specified by len.
from HERE