How do I append an item to an array in a pipeline?
Piping for loop output prevents local variable modification
How would you count occurrences of a string (actually a char) within a string? I am doing something where I realised I wanted to count how many /s I could find in a string, and then it struck me, that there were several ways to do it, but couldn't decide on what the best (or easiest) was.  At the moment I'm going with something like:  string source = "/once/upon/a/time/"; int count = source.Length - source.Replace("/", "").Length;   But I don't like it at all, any takers?  I don't really want to dig out RegEx for this, do I?  I know my string is going to have the term I'm searching for, so you can assume that...  Of course for strings where length > 1,  string haystack = "/once/upon/a/time"; string needle = "/"; int needleCount = ( haystack.Length - haystack.Replace(needle,"").Length ) / needle.Length; Prove that there are infinitely many primes and non-primes in the numbers $10^n+1$, where $n$ is a natural number. So numbers are 101, 1001, 10001 etc. How do I execute PHP that is stored in a MySQL database? I'm trying to write a page that calls PHP that's stored in a MySQL database. The page that is stored in the MySQL database contains PHP (and HTML) code which I want to run on page load.  How could I go about doing this? Ring of $\mathbb{Z}_2$-valued functions Let $R =\{f:\{1,2,3,4,\cdots ,10\}\to \mathbb{Z}_2 \}$ be the set of  all $\mathbb{Z}_2$ -valued functions on the set $\{1,2,3......10\}$  of the first ten positive integer. Then $R$ is a commutative ring with point-wise addition and multiplication of functions. Which of the following is true?     1) $R$ has a unique maximal ideal.      2) Every prime ideal of $R$ is also maximal.      3 ) The number of proper ideals of $R$ is $511$.      4 ) Every element of $R$ is idempotent.   R is finite commutative ring so  every prime ideal  is maximlal ideal ,so I think option  2 is true   .But for the other options   I am  helpless  . Force figure placement in text I have a problem when a lot of figures are in question. Some figures tend to "fly around", that is, be a paragraph below, although I placed them before that paragraph. I use code:  \begin{figure}[ht] \begin{center} \advance\leftskip-3cm \advance\rightskip-3cm \includegraphics[keepaspectratio=true,scale=0.6]{slike/visina8} \caption{} \label{visina8} \end{center}\end{figure}   to place my figures. How can I tell latex I REALLY want the figure in that specific place, no matter how much whitespace will be left? Is there a statement whose undecidability is undecidable? We know there are statements that are undecidable/independent of ZFC. Can there be a statement S, such that (ZFC $\not\vdash$ S and ZFC $\not\vdash$ ~S) is undecidable? In my game, XP needed to reach the next level is Current Level × Level Threshold.  Given that, how can I get my current level from the total XP ever earned?    For example:  Level Threshold = 50 Current Level = 1   Starting at level 1, I would need (1 × 50) = 50 XP to get to level 2, and so on.  Level 1: 50 XP needed to reach level 2 Level 2: 100 more XP needed to reach level 3 Level 3: 150 more XP needed to reach level 4   In other words, the progression table is as follows:  Level 1: 0 XP to 49 XP Level 2: 50 XP to 149 XP  Level 3: 150 XP to 299 XP Level 4: 300 XP to 499 XP   If I have 300 XP, I'll just reached level 4. How can I calculate that generally? Choosing Geographical Coordinate System and Projected Coordinate System for India? I want to create spatial data for entire India.  Usually I use WGS84 as GCS and UTM zones for PCS in the places in India, but when I have to create the spatial data for entire India, I get confused which geographical coordinate systems and projected coordinate system will be suitable.  What are suitable ones? String replace method is not replacing characters For linear regression, we can check the diagnostic plots (residuals plots, Normal QQ plots, etc) to check if the assumptions of linear regression are violated.  For logistic regression, I am having trouble finding resources that explain how to diagnose the logistic regression model fit. Digging up some course notes for GLM, it simply states that checking the residuals is not helpful for performing diagnosis for a logistic regression fit.  Looking around the internet, there also seems to be various "diagnosis" procedures, such as checking the model deviance and performing chi-squared tests, but other sources state that this is inappropriate, and that you should perform a Hosmer-Lemeshow goodness of fit test. Then I find other sources that state that this test may be highly dependent on the actual groupings and cut-off values (may not be reliable).  So how should one diagnose the logistic regression fit? Do any clones refuse Order 66? When the clones are issued      telling them to turn on the Jedi,    do any of them refuse to carry out the order? I have a Python script which I would like to execute at every startup. I can run it by adding this to the startup applications:  python3 /path/to/script.py   That works, but it doesn't open a terminal window, so I can't see the program's output. How could I make it open a terminal window and execute the script in there?  Note: I get the window to stay open with input(' ') at the end of the Python script. Thanks! PHP MySQLi doesn't recognize login info Is there a 'rule of thumb' on the upper limit of how many related records in related objects an object should have to avoid slow page loading? Typically, each record in Salesforce will be 2kb large: .   However, let's say in an extreme example, the Opportunity object is related to 40 custom objects, each which has 100,000 records. The page would load much slower, especially in an older browser version.   1) Is there a 'rule of thumb' as to what the upper limit of how many related records an object should have?   2) Also, , there's an indication that there's some sort of tier-tuning per org based on the volume of data it has. Is that correct? And if so, are the volume ranges and respective tier-tuning capacity available? How do I find the privileges I have earned and will earn in Stack Overflow? It used to be off the top bar, now its gone  Where has it moved?  EDIT:  It moved onto the profile page !  Right side same row as your name in profile:    Thank you De Rham Cohomology of the tangent bundle of a manifold I would like to compute the de Rham cohomology of the tangent bundle $TM$ of a manifold $M$. It seems to me that we can just homotopy each fibre to a point, and that this would give a homotopy equivalence between $TM$ and $M$. Since de Rham cohomology is a homotopy invariant, this would imply that $H^*_{\text{dR}}(TM) \cong H^*_{\text{dR}}(M)$.     Is it always true that the tangent bundle of a manifold is homotopic to the manifold itself by the homotopy of each fibre with a point? I did some mathematical induction problems on divisibility   $9^n$ $-$ $2^n$ is divisible by 7. $4^n$ $-$ $1$ is divisible by 3. $9^n$ $-$ $4^n$ is divisible by 5.   Can these be generalized as $a^n$ $-$ $b^n$$ = (a-b)N$, where N is an integer? But why is $a^n$ $-$ $b^n$$ = (a-b)N$ ?  I also see that $6^n$ $- 5n + 4$ is divisible by $5$ which is $6-5+4$ and $7^n$$+3n + 8$ is divisible by $9$ which is $7+3+8=18=9\cdot2$.  Are they just a coincidence or is there a theory behind?  Is it about modular arithmetic? How do I transfer my Destiny account from Xbox 360 to Xbox One? macOS: Is there a way to show an image constantly on screen (like a watermark)? I'm looking for a very simple way to add a watermark to my screen which should be shown whatever I'm doing, is it during a Zoom call, or is it when giving a presentation, or similar (I don't necessarily need it to show during fullscreen mode). The reason is that I want to record my screen using QuickTime Player, and the watermark should be on the video. I know that there are many post-production tools that offer adding watermarks, but I don't want to do any post-production, I want to have everything on screen while recording already. (I also know that there are screen recorders which offer placing a watermark to the end result. I'd rather also avoid using another screen recording software, but if I don't find any other way to do it, then I'm open to a simple, non-pricy alternative to QuickTime Player.) 'sudo su -' vs 'sudo -i' vs 'sudo /bin/bash' - when does it matter which is used, or does it matter at all?