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  • How to write a datatable to excel work book at client side

    - by senthilkumar
    Hi Guys Currently i am doing one project in that we need to generate report from database. Since my server memory is too low im getting 'Out of Memory' Exception when im writing it at serverside and also when i write directly to a excel file using http header as excel file im not able to create multiple sheets since my database table is huge more than 65536 rows. I saw many solution using a third party tool but i cant use those into mine..If anyone already worked on this please give me some direction. Also i tried using javascript but for that i need to use datagrid at server side?? but in my project i m not allowed to use like this.

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  • Type Declaration - Pointer Asterisk Position

    - by sahs
    Hello, in C++, the following means "allocate memory for an int pointer": int* number; So, the asterisk is part of the variable type; without it, that would mean something else (that's why I usually don't separate the asterisk from the variable type). Then what is the reason the asterisk is considered something else, instead of being part of the type? For example, it seems better, if the following meant "allocate memory for two int pointers": int* number1, number2; Am I wrong?

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  • How to return a string literal from a function

    - by skydoor
    Hi I am always confused about return a string literal or a string from a function. I was told that there might be memory leak because you don't know when the memory will be deleted? For example, in the code below, how to implement foo() so that make the output of the code is "Hello World"? void foo ( ) // you can add parameters here. { } int main () { char *c; foo ( ); printf ("%s",c); return 0; } Also if the return type of foo() is not void, but you can return char*, what should it be.

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  • C++ conditional compilation

    - by Shaown
    I have the following code snippet #ifdef DO_LOG #define log(p) record(p) #else #define log(p) #endif void record(char *data){ ..... ..... } Now if I call log("hello world") in my code and DO_LOG isn't defined, will the line be compiled, in other words will it eat up the memory for the string "hello world"? P.S. There are a lot of record calls in the program and it is memory sensitive, so is there any other way to conditionally compile so that it only depends on the #define DO_LOG? Thanks in advance.

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  • Read random lines from huge CSV file in Python

    - by jbssm
    I have this quite big CSV file (15 Gb) and I need to read about 1 million random lines from it. As far as I can see - and implement - the CSV utility in Python only allows to iterate sequentially in the file. It's very memory consuming to read the all file into memory to use some random choosing and it's very time consuming to go trough all the file and discard some values and choose others, so, is there anyway to choose some random line from the CSV file and read only that line? I tried without success: import csv with open('linear_e_LAN2A_F_0_435keV.csv') as file: reader = csv.reader(file) print reader[someRandomInteger] A sample of the CSV file: 331.093,329.735 251.188,249.994 374.468,373.782 295.643,295.159 83.9058,0 380.709,116.221 352.238,351.891 183.809,182.615 257.277,201.302 61.4598,40.7106

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  • are runtime linking library globals shared among plugins loaded with dlopen?

    - by conejoroy
    I've a C++ program that links at runtime with, lets say, mylib.so. then, the same program uses dlopen()/dlsym() to load a function from myplugin.so, dynamic library that in turn has dependencies to mylib.so. My question is: will the program AND the function in the plugin access the same globals defined in mydlib.so in the same memory area reserved for the program, or each will be assigned different, unrelated copies in its own memory space? if the latter is the default behaviour, is it possible to change that? Thanks in advance =)!

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  • How can I position QDockWidgets as the screen shot shows using code?

    - by Nathan
    I want a Qt window to come up with the following arrangement of dock widgets on the right. Qt allows you to provide an argument to the addDockWidget method of QMainWindow to specify the position (top, bottom, left or right) but apparently not how two QDockWidgets placed on the same side will be arranged. Here is the code that adds the dock widgets. this uses PyQt4 but it should be the same for Qt with C++ self.memUseGraph = mem_use_widget(self) self.memUseDock = QDockWidget("Memory Usage") self.memUseDock.setObjectName("Memory Usage") self.memUseDock.setWidget(self.memUseGraph) self.addDockWidget(Qt.DockWidgetArea(Qt.RightDockWidgetArea),self.memUseDock) self.diskUsageGraph = disk_usage_widget(self) self.diskUsageDock = QDockWidget("Disk Usage") self.diskUsageDock.setObjectName("Disk Usage") self.diskUsageDock.setWidget(self.diskUsageGraph) self.addDockWidget(Qt.DockWidgetArea(Qt.RightDockWidgetArea),self.diskUsageDock) When this code is used to add both of them to the right side, one is above the other, not like the screen shot I made. The way I made that shot was to drag them there with the mouse after starting the program, but I need it to start that way.

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  • Side effects of reordering columns in PostgreSQL

    - by Summer
    I sometimes re-order the columns in my Postgres DB. Since Postgres can only add columns at the end of tables, I end up re-ordering by adding new columns at the end of the table, setting them equal to existing columns, and then dropping the original columns. My question is: what does PostgreSQL do with the memory that's freed by dropped columns? Does it automatically re-use the memory, so a single record consumes the same amount of space as it did beforehand? But that would require a re-write of the whole table, so to avoid that, does it just keep a bunch of blank space around in each record? Thanks! ~S

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  • How Flask loads blueprint internaly?

    - by Ignas B.
    I'm just interested how Flask's blueprints gets imported. It still imports the python module at the end of all the stuff done by Flask and if I'm right python does two things when importing: registers the module name in the namespace and then initialize it if needed. So if Flask blueprint is initialized when it gets registered, so all the module then is in memory and if there are lots of blueprints to register, the memory just gets wasted, because in one request basically you use one blueprint. Not a big loss but still... But if it is only registered in the namespace and initialized only when needed (when the real request reaches it), then it make sense to register them all at once (as is the recommended way I understood). This is I guess the case here :) But just wanted to ask and understand a bit deeper.

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  • Why oh why doesn't my asp.net treeview update?

    - by Brendan
    I'm using an ASP.net treeview on a page with a custom XmlDataSource. When the user clicks on a node of the tree, a detailsview pops up and edits a bunch of things about the underlying object. All this works properly, and the underlying object gets updated in my background object-management classes. Yay! However, my treeview just isn't updating the display. Either immediately (which i would like it to), or on full page re-load (which is the minimal useful level i need it to be at). Am i subclassing XmlDataSource poorly? I really don't know. Can anyone point me in a good direction? Thanks! The markup looks about like this (chaff removed): <data:DefinitionDataSource runat="server" ID="DefinitionTreeSource" RootDefinitionID="uri:1"></data:DefinitionDataSource> <asp:TreeView ID="TreeView" runat="server" DataSourceID="DefinitionTreeSource"> <DataBindings> <asp:TreeNodeBinding DataMember="definition" TextField="name" ValueField="id" /> </DataBindings> </asp:TreeView> <asp:DetailsView ID="DetailsView1" runat="server" AutoGenerateRows="False" DataKeyNames="Id" DataSourceID="DefinitionSource" DefaultMode="Edit"> <Fields> <asp:BoundField DataField="Name" HeaderText="Name" HeaderStyle-Wrap="false" SortExpression="Name" /> <asp:CommandField ShowCancelButton="False" ShowInsertButton="True" ShowEditButton="True" ButtonType="Button" /> </Fields> </asp:DetailsView> And the DefinitionTreeSource code looks like this: public class DefinitionDataSource : XmlDataSource { public string RootDefinitionID { get { if (ViewState["RootDefinitionID"] != null) return ViewState["RootDefinitionID"] as String; return null; } set { if (!Object.Equals(ViewState["RootDefinitionID"], value)) { ViewState["RootDefinitionID"] = value; DataBind(); } } } public DefinitionDataSource() { } public override void DataBind() { base.DataBind(); setData(); } private void setData() { String defXML = "<?xml version=\"1.0\" ?>"; Test.Management.TestManager.Definition root = Test.Management.TestManager.Definition.GetDefinitionById(RootDefinitionID); if (root != null) this.Data = defXML + root.ToXMLString(); else this.Data = defXML + "<definition id=\"null\" name=\"Set Root Node\" />"; } } }

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  • Efficient alternatives to merge for larger data.frames R

    - by Etienne Low-Décarie
    I am looking for an efficient (both computer resource wise and learning/implementation wise) method to merge two larger (size1 million / 300 KB RData file) data frames. "merge" in base R and "join" in plyr appear to use up all my memory effectively crashing my system. Example load test data frame and try test.merged<-merge(test, test) or test.merged<-join(test, test, type="all") - The following post provides a list of merge and alternatives: How to join data frames in R (inner, outer, left, right)? The following allows object size inspection: https://heuristically.wordpress.com/2010/01/04/r-memory-usage-statistics-variable/ Data produced by anonym

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  • Threaded Django task doesn't automatically handle transactions or db connections?

    - by Gabriel Hurley
    I've got Django set up to run some recurring tasks in their own threads, and I noticed that they were always leaving behind unfinished database connection processes (pgsql "Idle In Transaction"). I looked through the Postgres logs and found that the transactions weren't being completed (no ROLLBACK). I tried using the various transaction decorators on my functions, no luck. I switched to manual transaction management and did the rollback manually, that worked, but still left the processes as "Idle". So then I called connection.close(), and all is well. But I'm left wondering, why doesn't Django's typical transaction and connection management work for these threaded tasks that are being spawned from the main Django thread?

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  • Maximum executable size on the iPhone?

    - by Sirp
    Is there a maximum size of executables or executables + shared objects on the iPhone? I've been developing an app that has been crashing on startup or early in execution with SIGSYS. Removing code from the program has helped, though structuring data so the code is simply not executed does not. This could be memory corruption, of some kind, however when I compiled with -Os rather than -O2 or -O3 the size of my executable goes down from 5.15MB to 3.60MB and the application runs perfectly. I also have a bunch of libraries I use, of course. I'm wondering, is there a limit on the size of executable code on the iPhone? Or am I just 'getting lucky' and masking memory corruption when I use -Os?

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  • What the best approach to iterate and "store" files over a directory in C (Linux) ?

    - by Andrei Ciobanu
    I have written a function that checks if to files are duplicates or not. This function signature is: int check_dup_memmap(char *f1_name, char *f2_name) It returns: (-1) - If something went wrong; (0) - If the two files are similar; (+1) - If the two files are different; The next step is to write a function that iterates through all the files in a certain directory,apply the previous function, and gives a report on every existing duplicates. Initially I've thought to write a function that generates a file with all the filenames in a certain directory and then, read that file again and gain and compare every two files. Here is that version of the function, that gets all the filenames in a certain directory. void *build_dir_tree(char *dirname, FILE *f) { DIR *cdir = NULL; struct dirent *ent = NULL; struct stat buf; if(f == NULL){ fprintf(stderr, "NULL file submitted. [build_dir_tree].\n"); exit(-1); } if(dirname == NULL){ fprintf(stderr, "NULL dirname submitted. [build_dir_tree].\n"); exit(-1); } if((cdir = opendir(dirname)) == NULL){ char emsg[MFILE_LEN]; sprintf(emsg, "Cannot open dir: %s [build_dir_tree]\t",dirname); perror(emsg); } chdir(dirname); while ((ent = readdir(cdir)) != NULL) { lstat(ent->d_name, &buf); if (S_ISDIR(buf.st_mode)) { if (strcmp(".", ent->d_name) == 0 || strcmp("..", ent->d_name) == 0) { continue; } build_dir_tree(ent->d_name, f); } else{ fprintf(f, "/%s/%s\n",util_get_cwd(),ent->d_name); } } chdir(".."); closedir(cdir); } Still I consider this approach a little inefficient, as I have to parse the file again and again. In your opinion what are other approaches should I follow: Write a datastructure and hold the files instead of writing them in the file ? I think for a directory with a lot of files, the memory will become very fragmented. Hold all the filenames in auto-expanding array, so that I can easy access every file by their index, because they will in a contiguous memory location. Map this file in memory using mmap() ? But mmap may fail, as the file gets to big. Any opinions on this. I want to choose the most efficient path, and access as few resources as possible. This is the requirement of the program... EDIT: Is there a way to get the numbers of files in a certain directory, without iterating through it ?

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  • how to install the IIS in windows 7 ?

    - by prateeksaluja20
    Hello Experts, I have tried to install IIS in My local machine in windows 7.My purpose is to install the IIS & change its Seesion timeout property bcoz I want to increase the Session time out Period.so I went to Control Panel-All Control Panel Items-Programs and Features then clicked Windows features on & off. after that clicked on Internet Information Service then Web Management Tool then IIS Management Console then pressed ok. It installed but when i went to see in Inetpub\wwwroot I got nothing.when i went to see "http:\localhost\" result shown blank page. i tried to search in Google but still i Don't get the answer.so plz help me shortout this problem. Thanx.

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  • Anyone Know a Great Sparse One Dimensional Array Library in Python?

    - by TheJacobTaylor
    I am working on an algorithm in Python that uses arrays heavily. The arrays are typically sparse and are read from and written to constantly. I am currently using relatively large native arrays and the performance is good but the memory usage is high (as expected). I would like to be able to have the array implementation not waste space for values that are not used and allow an index offset other than zero. As an example, if my numbers start at 1,000,000 I would like to be able to index my array starting at 1,000,000 and not be required to waste memory with a million unused values. Array reads and writes needs to be fast. Expanding into new territory can be a small delay but reads and writes should be O(1) if possible. Does anybody know of a library that can do it? Thanks!

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  • python dictionary with constant value-type

    - by s.kap
    hi there, I bumped into a case where I need a big (=huge) python dictionary, which turned to be quite memory-consuming. However, since all of the values are of a single type (long) - as well as the keys, I figured I can use python (or numpy, doesn't really matter) array for the values ; and wrap the needed interface (in: x ; out: d[x]) with an object which actually uses these arrays for the keys and values storage. I can use a index-conversion object (input -- index, of 1..n, where n is the different-values counter), and return array[index]. I can elaborate on some techniques of how to implement such an indexing-methods with reasonable memory requirement, it works and even pretty good. However, I wonder if there is such a data-structure-object already exists (in python, or wrapped to python from C/++), in any package (I checked collections, and some Google searches). Any comment will be welcome, thanks.

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  • Loading a Windows DLL in Java and initiate a class from it

    - by Joy
    I have a Windows DLL file from .NET namely "System.Management.dll". I work with it using the code I write below: ManagementObjectSearcher searcher = new ManagementObjectSearcher("root\\CIMV2", "SELECT * FROM Win32_LogicalDisk WHERE Name = 'C:'"); foreach (ManagementObject queryObj in searcher.Get()) { Console.WriteLine("Win32_LogicalDisk instance: "); if (queryObj["VolumeSerialNumber"] != null) { Console.WriteLine("Drive Name : " + queryObj["Name"]); Console.WriteLine("VolumeSerialNumber:", queryObj["VolumeSerialNumber"]); SysdriveSerial = queryObj["VolumeSerialNumber"].ToString(); } } Now I need this piece of code to be in Java. So can I do this? Without anything like c++ unmanaged code. I don't want to use c++ unmanaged code to call to this dll. I want something like this : public class CallToCsharp { private static native void ManagementObjectSearcher(); public static void main(String[] args) { System.loadLibrary("System.Management"); System.out.println("Loaded"); ManagementObjectSearcher searcher = new ManagementObjectSearcher("root\\CIMV2", "SELECT * FROM Win32_LogicalDisk WHERE Name = 'C:'"); } }

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  • C++: Why don't I need to check if references are invalid/null?

    - by jbu
    Hi all, Reading http://www.cprogramming.com/tutorial/references.html, it says: In general, references should always be valid because you must always initialize a reference. This means that barring some bizarre circumstances (see below), you can be certain that using a reference is just like using a plain old non-reference variable. You don't need to check to make sure that a reference isn't pointing to NULL, and you won't get bitten by an uninitialized reference that you forgot to allocate memory for. My question is how do I know that the object's memory hasn't been freed/deleted AFTER you've initialized the reference. What it comes down to is that I can't take this advice on faith and I need a better explanation. Can anyone shed some light? Thanks, jbu

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  • In a virtual machine monitor such as VMware's ESXi Server, how are shadow page tables implemented?

    - by ali01
    My understanding is that VMMs such as VMware's ESXi Server maintain shadow page tables to map virtual page addresses of guest operating systems directly to machine (hardware) addresses. I've been told that shadow page tables are then used directly by the processor's paging hardware to allow memory access in the VM to execute without translation overhead. I would like to understand a bit more about how the shadow page table mechanism works in a VMM. Is my high level understanding above correct? What kind of data structures are used in the implementation of shadow page tables? What is the flow of control from the guest operating system all the way to the hardware? How are memory access translations made for a guest operating system before its shadow page table is populated? How is page sharing supported? Short of straight up reading the source code of an open source VMM, what resources can I look into to learn more about hardware virtualization?

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  • data structure for counting frequencies in a database table-like format

    - by user373312
    i was wondering if there is a data structure optimized to count frequencies against data that is stored in a database table-like format. for example, the data comes in a (comma) delimited format below. col1, col2, col3 x, a, green x, b, blue ... y, c, green now i simply want to count the frequency of col1=x or col1=x and col2=green. i have been storing the data in a database table, but in my profiling and from empirical observation, database connection is the bottle-neck. i have tried using in-memory database solutions too, and that works quite well; the only problem is memory requirements and quirky init/destroy calls. also, i work mainly with java, but have experience with .net, and was wondering if there was any api to work with "tabular" data in a linq way using java. any help is appreciated.

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