Harleen Sahni
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Objects are true, but the undefined value and null are both false. The double negation operator !! calculates the truth value of a value. It's actually two operators, where !!x means !(!x), and behaves as follows: If x is a false value, !x is true, and !!x is false. If x is a true value, !x is false, and !!x is true.
Nov 27, 2020 · (bang-bang) was what I needed to force eval of the content of the variable; however, I did not get the expected output in my new column. Only the !!as.name gave me the output I was expecting, and I do not fully understand why. Could someone explain why in this case using only !! isn't appropriate and what is happening in !!as.name?
Feb 16, 2017 · AFAIK came from the C# land. With nullable types, C# got its bang too (pun, of course, intended). Yup, the Sir Tony's invention wroke a serious havoc on the world of procedural programming, and we still cleaning the fallout. Being the sweetest person, he still apologizes for it. Curiously, his major contribs to CS are in automatic reasoning ...
Nov 4, 2021 · Its a bang-bang operator used to force early evaluation of part of an expression before it gets fully evaluated. So, its forcing to evaluate that part of the expression before the rest. With more input, I could provide a more detailed answer. answered Nov 4, 2021 at 17:51. Spartacus Rocha.
Nov 18, 2020 · I'd like to make a simple function that takes a data frame and user supplied names for two columns in that data frame.
Apr 30, 2012 · Feb 3, 2022 at 18:24. 3. #!/usr/bin/env bash poses a privilege escalation security threat when a suid program executes a bash script that has such a shebang. The user can simply manipulate his PATH and get an arbitrary bash executable to be run instead, with elevated privileges.
Jan 20, 2018 · Kotlin's double-bang operator is an excellent sample for fans of NullPointerException (NPE). The not-null assertion operator !! converts any value to a non-null type and throws an exception if the value is null. val nonNull = str!!.length. If you write str!!, it'll return a non-null value of str (str is a String? here) or throw an NPE if str is ...
The bang bang (!!) command is a shortcut to repeat the previous command you entered in your terminal. This command is very useful when you forget that you need admin rights to make a certain action, and lets you repeat it with super-user rights just by typing. sudo !! instead of typing arrow-up, scrolling to the beginning of the line, adding ...
Apr 29, 2011 · Out of curiosity, I noticed that no bang and bang perform the fastest but somewhere in the evolution of Chrome at least, bang became faster than no bang. (Probably statistically insignificant but...) Is there a reason why? I don't know much about code beneath the hood but find it quite fascinating. –
So what does this do? If the operand is 0, the inner ! converts it to 1, then the outer ! converts that to 0. If the operand is non-zero, the inner ! converts it to 0, then the outer ! converts that to 1. So !! converts a value to its boolean equivalent. If the value is 0, it remains 0, otherwise it becomes 1.
