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Showing posts from April, 2017

Reverse a number without converting to a string.

Sometimes I like to work on coding problems just for fun. Things like Project Euler, Code Eval Hackerrank etc. Depending on what language you decide to do things in it might be easier and more efficient to think a little different.
Some languages like Ruby, for example, converting a number to a string with to_str() and then reversing is rather trivial. But what if I want to solve it by keeping the number a number?
Currently, I am playing around with Rust so my example will be in that language however you can use this same formula in whatever language you like.
pub fn num_reverse(number: i32) -> i32 { let mut num = number; let mut rev = 0; while num > 0 { rev = rev * 10 + (num % 10); num = num / 10; } return rev; } Now that we have the code lets map out a little bit of how it works. Let us take the number 1234.
num = 1234; rev = 0; Grab the first digit.
rev = rev * 10 + (num % 10)
Which can be written as.
rev = 0 * 10 + (1234 % 10…

Remote API useful tricks for Docker on Mac OS X

Install Socat Socat allow you to forward ports to a variety of things. For Docker forwarding a port to the docker.sock file makes a quick way to get access to the Docker remote api.
Docker also allow a way to open up that TCP port however on Mac it is temperamental and hard to use
brew install socat socat -d TCP-LISTEN:2375,reuseaddr,fork UNIX:/var/run/docker.sock & Create an IP alias Running Docker containers locally is a fairly common thing. Interconnectivity between containers works naturally. However, sometimes you may also want a container to connect back to the Docker Remote API. If you are constantly on the go changing networks you do not want to have to change that IP address every time.
A great use case for this is running Jenkins and using docker slaves
sudo ifconfig lo0 alias Remote API There are also some interesting endpoints you can use for information
curl http://localhost:2375 curl http://localhost:2375/containers/json curl http://localhost:2375…