Consider a simple function that adds the first N natural numbers. (e.g. sum(5) = 0 + 1 + 2 + 3 + 4 + 5 = 15). Here is a simple JavaScript implementation that uses recursion: If you called recsum(5), this is what the JavaScript interpreter would evaluate: Note how every recursive call has to complete before … Read more
In all languages that support an operator := it means assignment. In languages that support an operator :=, the = operator usually means an equality comparison. In languages where = means assignment, == is typically used for equality comparison. does := mean =? I can’t recall any languages where := means the same as =. In MySQL := and = are both used for assignment, however they are not interchangeable and selecting the correct one … Read more
Instance variable is the variable declared inside a class, but outside a method: something like: Now this IronMan Class can be instantiated in another class to use these variables. Something like: This is how we use the instance variables. Shameless plug: This example was pulled from this free e-book here here.
An npm script is just a shortcut to run a series of node commands on your project. Any npm script, meaning any node.js commands listed under a package.json file’s “scripts” section, are executed through node.js when you call them. So npm start runs the node script that is listed under start in the package.json. As in the article that … Read more
It’s a(n insecure) remote shell introduced by the target. That’s the opposite of a “normal” remote shell, that is introduced by the source. Let’s try it with localhost instead of 10.0.0.1: Open two tabs in your terminal. open TCP port 8080 and wait for a connection:nc localhost -lp 8080 Open an interactive shell, and redirect the IO streams … Read more
Authentication is the process of ascertaining that somebody really is who they claim to be. Authorization refers to rules that determine who is allowed to do what. E.g. Adam may be authorized to create and delete databases, while Usama is only authorised to read. The two concepts are completely orthogonal and independent, but both are central to security design, … Read more
Destination Host Unreachable This message indicates one of two problems: either the local system has no route to the desired destination, or a remote router reports that it has no route to the destination. If the message is simply “Destination Host Unreachable,” then there is no route from the local system, and the packets to … Read more
The stack is the memory set aside as scratch space for a thread of execution. When a function is called, a block is reserved on the top of the stack for local variables and some bookkeeping data. When that function returns, the block becomes unused and can be used the next time a function is … Read more
I think you are mixing up lots of different things and have several confusions, so I’m try to work through most of them in the order you brought them up: when we declare a series of vertices, let’s say 3 vertices that form a triangle primitive, we basically store those nowhere, they’re simply declared in … Read more
nslookup google.com is the easiest way. Works on Linux and Windows. If your issue is that your DNS server is not returning a response for google.com, use a different DNS server, such as a public one. For instance, you could do: nslookup>server 8.8.8.8>google.com For a more thorough solution to getting around annoying Internet filters, look … Read more