I am trying to utilize c++ in embeded application. and i ran into a theoretical problem  Given that i have no dynamic allocation i dont use "new" operator. The question is regarding calling constructor for object and destructor.   I would like to put my object at x address in memory. i declare it like that:   Foo *myClass = (Foo *) 0x1; //for example //I guess i need to call constructor manually ? myClass-&gt;myClass();   So what would be a solution to call the constructor other then manually invoke it. Should i just make a new operator my self ? for example  void * operator new(size_t size, uint32_t address) {   return (void *)(address);  }   compiler used arm-none-eabi-g++, target armv7-m
I just learned about the C++ construct called "placement new".  It allows you to exactly control where a pointer points to in memory.  It looks like this:   #include &lt;new&gt;        // Must #include this to use "placement new"  #include "Fred.h"     // Declaration of class Fred   void someCode()  {    char memory[sizeof(Fred)];    void* place = memory;     Fred* f = new(place) Fred();   // Create a pointer to a Fred(),                                   // stored at "place"     // The pointers f and place will be equal     ...  }    (example from ) In this example, the this pointer of Fred will be equal to place.    I've seen it used in our team's code once or twice.  In your experience, what does this construct enable?  Do other pointer languages have similar constructs?  To me, it seems reminiscent of equivalence in FORTRAN, which allows disparate variables to occupy the same location in memory.
I've seen some of the other threads on using strings as x axis labels, but nothing that fits my situation.  I'm trying to create a bar chart from a CSV file. I can do it so long as everything in the data is numeric. However, in my actual data table, the first row is multi-word string descriptions. I need these descriptions to be the x axis labels for each bar.  I've tried symbolic x coords, but I get the "could not parse input as a floating point number" error. I've also tried adding an ID column and using that as the x values, and assigning xtick labels as the string descriptors. I get the same issue that way.  Here's an attempt at an MWE:  \documentclass{article}  \usepackage{lmodern} \usepackage{tikz} \usepackage{pgfplots} \usepackage{pgfplotstable}  \begin{document}  \pgfplotstabletypeset[columns/category/.style={string type},col sep=comma]{Book3.csv} \vspace{1cm}  \begin{tikzpicture} \begin{axis}[ ybar, xlabel=Xstuff, ylabel=Value, symbolic x coords={cat a,cat b,cat c,cat d,cat e,cat f,cat g}, %xtick labels={cat a,cat b,cat c,cat d,cat e,cat f,cat g},% this is from when i tried the xtick label method xtick=data, nodes near coords, nodes near coords align={vertical}] \addplot table[x=category,y=value]{Book3.csv}; %\addplot table[x=category,y=value]{Book3.csv};&amp; again, from trying the xtick label method  \end{axis}  \end{tikzpicture} \end{document}   Since I suspect this might get answered quickly by you chart gurus, I have a follow-up question:  I have to do a bunch of these charts, and I would like to automate the symbolic x coords process. Is there a way to populate the dictionary of accepted x coords by reading a column of the data? (something like symbolic x coords={columns/category/{Book3.csv}} )?  Book3.csv looks like this (ignore the ID column if using the xtick label method):  ID, category, value, value 2 1,  cat a,    1,     7 2,  cat b,    2,     6 3,  cat c,    3,     5 4,  cat d,    4,     4 5,  cat e,    5,     3 6,  cat f,    6,     2 7,  cat g,    7,     1 This is a revisit of  that seems to have grown stale without any solid answer. Just recently I was baffled by 's ability to :  In my experience, certain review queues seem to be more inclined to &quot;single-user reviews&quot; (like First Posts and/or Late Answers), while others are more geared to &quot;multi-user reviews&quot; (like Close Votes and/or Suggested Edits). This does not seem to be the case here. The &quot;requirement&quot; for such late, duplicate reviews are questionable and               (         ). Even being able to  (I highly doubt this was an instance of keeping the review window open for more than an hour and only reviewing it post mortem - first post reviews are dealt with far more quickly than most other review queues):   While these examples do not speak to the , it sure seems biased. Something is amiss... Over at  we have a far smaller community, so these situations are far more noticeable.  Edit: The following are all candidates for the above discussion: Is there a word which describes terms that are spelled like a particular pronunciation? Some examples: &quot;never&quot; might be written as &quot;neva&quot; &quot;I don't know&quot; is sometimes written as &quot;iono&quot; or &quot;I dunno&quot; on various internet media. My question is: is there a word for this particular technique of spelling a term in the way it is (sometimes) pronounced? How to test multiple variables against a single value? Database files that are built using SQL 2008 are not compatable with 2005. Is there a work around? Do I need a UK visa? How and where to apply? disable clickable landmark on google map If n is such that every element $(\mathbb{Z}/n\mathbb{Z})^{\times}$ is a root of $x^2-1$. Prove that $n$ divides 24. I have a hard time formulating proofs.  For this problem, I  can see that if $n$ is equal to $8,$ this statement is true.  $(\mathbb{Z}/8\mathbb{Z})^{\times}$ includes elements:  $1,3,5,7$, and all of these are roots of $1-x^2 \pmod 8.$  And obviously $8$ divides $24.$  But how do I prove this without depending on number calculations and only using theorems?  Help Please?  I need a step by step walk through of how to do this proof and what theorems would be appropriate to use. I read somewhere that companies are not required to pay dividends to shareholders (this is correct, yes?).   If so, then if company A never pays dividends to its shareholders, then what is the point of owning company A's stock? Surely the right to one vote for company A's Board can't be that valuable.   What is it that I'm missing? I have the following annoying problem with Excel 2010. I use Conditional formatting to apply bold formatting to each line of the spreadsheet that meets a condition expressed by a formula. In the "applies to", I write =$A$2:$Q$149, which is the current extent of my spreadsheet. But I want this range to grow with my spreadsheet, i.e., I want the formatting to permanently apply to the whole spreadsheet. Regularly, my "applies to" field is transformed into a complex range, that selects most lines of spreadsheet, but not all, like =$A$2:$Q$138;$A$140:$Q$147. Have you ever encountered such a problem? Is there a solution? I would like to hide all items that I don't need from appearing in App Lens.  For example: XTerm, File Roller and the Home Folder.  Is this possible? How can I record my screen on Ubuntu?   The app I'm looking for has ideally all of these features:   Can record in a format that can be played back easily on any platform and/or accepted by YouTube or another popular video site Can record just a window (instead of the whole screen), possibly selecting it with a mouse click Can start recording after a configurable delay (e.g., I launch the app and have time to do arrangements to my desktop/window before actual recording starts) Filtering points in GeoServer layer Is the sign of principal components meaningless? For all $1 \leq i < j \leq k$, the subtrees $T_i$ and $T_j$ have a vertex in common. Show that $T$ has a vertex which is in all of the $T_i$. Can someone please verify my proof or offer suggestions for improvement? I am aware that there is a similar question elsewhere, but I want help with my proof in particular.     Let $T_1, \ldots, T_k$ be subtrees of a tree $T$ such that for all $1 \leq i &lt; j \leq k$, the trees $T_i$ and $T_j$ have a vertex in common. Show that $T$ has a vertex which is in all of the $T_i$.   Suppose, for the sake of contradiction, that for every vertex $v \in V(T)$, there is a subtree $T'$ in the list $T_1, T_2, \ldots, T_k$ such that $v \notin V(T')$.  Pick $v_1 \in T_1$. There is a subtree $T^{(1)}$ such that $v_1 \notin T^{(1)}$. $T_1$ and $T^{(1)}$ have a vertex $y_1$ in common. Now, there exists a tree $T^{(2)}$ such that $y_1 \notin T^{(2)}$. But now, $T^{(2)}$ and $T^{(1)}$ have a vertex $y_2$ in common. Also, $T_1$ and $T^{(2)}$ have a vertex $y_3$ in common.  There exists a path $p_1$ in $T_1$ from $y_3$ to $y_1$. Also, there is a path $p_2$ in $T^{(1)}$ from $y_1$ to $y_2$ and a path $p_3$ in $T^{(2)}$ from $y_2$ to $y_3$. Note that the path formed by the union of $p_1$ and $p_2$ passes through $y_1$, while $p_3$ does not, since $y_1 \notin T^{(2)}$. Therefore, the union of $p_1, p_2$, and $p_3$ forms a cycle, contradicting the fact that $T$ is a tree. Therefore, it must be the case that there is a vertex $x$ in all of the $T_i$. I am making a regex expression in which I only want to match wrong tags like: &lt;p&gt; *some text here, some other tags may be here as well but no ending 'p' tag* &lt;/p&gt;   &lt;P&gt;Affectionately Inscribed &lt;/P&gt;&lt;P&gt;TO &lt;/P&gt;&lt;P&gt;HENRY BULLAR, &lt;/P&gt;&lt;P&gt;(of the western circuit)&lt;P&gt;PREFACE&lt;/P&gt;   In the above same text I want to get the result as  &lt;P&gt;(of the western circuit)&lt;P&gt; and nothing else should be captured. I'm using this but its not working:  &lt;P&gt;[^\(&lt;/P&gt;\)]*&lt;P&gt;   Please help. For example:     Is (A &or; B &or; C) &and; (D &or; E &or; F) the same as   (A &and; D) &or; (A &and; E) &or; (A &and; F) &or; (B &and; D) &or; (B &and; E) &or; ( B &and; F) &or; (C &and; D) &or; (C &and; E) &or; (C &and; F)?   How would I check equivalence in general? Default currency symbol I'm looking for a way to get the Default currency symbol (in a none-multi-currency org) of the salesforce org locale (to have it displayed on a visualforce page in a field that can't be &lt;apex:inputField&gt; or &lt;apex:outputField&gt;) preferably query-able from apex (via the database, a describe or whatever) and then again the actual symbol, meaning € for Euro, $ for dollar, and so on...  There must surely be some sort of mapping hidden in the code somewhere salesforce does this via the input/outputfields if bound to an sobject of type currency  Can anyone point me in the right direction? Comprehensive list of activation functions in neural networks with pros/cons Are there any reference document(s) that give a comprehensive list of activation functions in neural networks along with their pros/cons (and ideally some pointers to publications where they were successful or not so successful)? How to prove $\text{Rank}(AB)\leq \min(\text{Rank}(A), \text{Rank}(B))$?