The print() function writes, i.e., “prints”, a string in the console. The return statement causes your function to exit and hand back a value to its caller. The point of functions in general is to take in inputs and return something. The return statement is used when a function is ready to return a value to its caller. For example, here’s … Read more
In pthread_exit, ret is an input parameter. You are simply passing the address of a variable to the function. In pthread_join, ret is an output parameter. You get back a value from the function. Such value can, for example, be set to NULL. Long explanation: In pthread_join, you get back the address passed to pthread_exit by the finished thread. If you pass just a plain … Read more
It depends on how correct you want to be. \n will usually do the job. If you really want to get it right, you look up the newline character in the os package. (It’s actually called linesep.) Note: when writing to files using the Python API, do not use the os.linesep. Just use \n; Python automatically translates that to the proper newline … Read more
In Python, you can do: In Python 3.5, you can do: And then: Will always be true. Unless of course, as pointed out, x is also infinity or “nan” (“not a number”). Additionally (Python 2.x ONLY), in a comparison to Ellipsis, float(inf) is lesser, e.g: would return true.
Basically, you check if an object is an instance of a specific class. You normally use it, when you have a reference or parameter to an object that is of a super class or interface type and need to know whether the actual object has some other type (normally more concrete). Example: Note that if … Read more
Let me give some information on them: quit() simply raises the SystemExit exception.Furthermore, if you print it, it will give a message:>>> print (quit) Use quit() or Ctrl-Z plus Return to exit >>> This functionality was included to help people who do not know Python. After all, one of the most likely things a newbie will try to … Read more
git pull origin master pulls the master branch from the remote called origin into your current branch. It only affects your current branch, not your local master branch. It’ll give you history looking something like this: Your local master branch is irrelevant in this. git pull is essentially a combination of git fetch and git merge; it fetches the remote branch then … Read more
For problems where it seems to be an error on a line you think is correct, you can often remove/comment the line where the error appears to be and, if the error moves to the next line, there are two possibilities. Either both lines have a problem or the previous line has a problem which is being carried forward. … Read more
Xpenology isn’t a linux OS like Ubuntu or other common distribution. It’s a bootloader for synologys operating system DSM, which they use on their NAS devices. DSM is running on a custom linux version developed by Synology, so it’s also not real compareable to desktop/server distributions in a direct way. Its optimized for running on … Read more
UNION removes duplicate records (where all columns in the results are the same), UNION ALL does not. There is a performance hit when using UNION instead of UNION ALL, since the database server must do additional work to remove the duplicate rows, but usually you do not want the duplicates (especially when developing reports). UNION Example: Result: UNION ALL example: Result: