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Get current directory name (without full path) in a Bash script
...cause dirname has functionality that ${PWD##*/} does not -- transforming a string with no slashes to ., for instance. Thus, while using dirname as an external tool has performance overhead, it also has functionality that helps to compensate for same.
– Charles Duffy
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What is the maximum possible length of a .NET string?
What is the longest string that can be created in .NET? The docs for the String class are silent on this question as far as I can see, so an authoritative answer might require some knowledge of internals. Would the maximum change on a 64-bit system?
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MYSQL Truncated incorrect DOUBLE value
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Yes..i too had a similar experience while trying to use a string literal in 'where' clause without the using quotes.
– pranay
Feb 16 '19 at 18:02
1
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(![]+[])[+[]]… Explain why this works
...ition, an empty Array, [], this is made just to convert the false value to String, because the string representation of an empty array is just an empty string, is equivalent to:
false+[]; // "false"
false+''; // "false"
The last part, the pair of square brackets after the parentheses, they are th...
eval command in Bash and its typical uses
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eval takes a string as its argument, and evaluates it as if you'd typed that string on a command line. (If you pass several arguments, they are first joined with spaces between them.)
${$n} is a syntax error in bash. Inside the braces, y...
SQL order string as number
...o number
select col from yourtable
order by col + 0
BTW MySQL converts strings from left to right. Examples:
string value | integer value after conversion
--------------+--------------------------------
'1' | 1
'ABC' | 0 /* the string does not contain a number, so the re...
Delete empty lines using sed
...y here means, the line contains no chars, or the line contains only empty strings (E.g. spaces). All matched lines will be removed by sed, with the d command.
– Kent
Feb 26 '17 at 19:41
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Create a unique number with javascript time
...bit of processing:
var now = new Date();
timestamp = now.getFullYear().toString(); // 2011
timestamp += (now.getMonth < 9 ? '0' : '') + now.getMonth().toString(); // JS months are 0-based, so +1 and pad with 0's
timestamp += ((now.getDate < 10) ? '0' : '') + now.getDate().toString(); // pad ...
ActiveRecord: size vs count
...many association, size will use the cached count directly, and not make an extra query at all.
class Image < ActiveRecord::Base
belongs_to :product, counter_cache: true
end
class Product < ActiveRecord::Base
has_many :images
end
> product = Product.first # query, load product into m...
onKeyPress Vs. onKeyUp and onKeyDown
... an empty input element:
The value of the input element will be an empty string (old value) inside the keypress handler
The value of the input element will be 1 (new value) inside the keyup handler.
This is of critical importance if you are doing something that relies on knowing the new value af...