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Search found 616 results on 25 pages for 'clueless anon'.

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  • MacOSX: OSAtomic vs OSAtomicBarrier

    - by anon
    For the functions here: #include <libkern/OSAtomic.h> there are OSAtomic and OSAtomicBarrier versions. However, the documentation does not show sample code for: When is it safe to use just OSAtomic, without the OSAtomicBarrier version When is it that OSAtomic would be unsafe, but OSAtomiBarrier would be safe. Can anyone provide explainations + sample codes? [Random ramblings of "your opinion" without actual code is useless. Readers: please down vote such answers; and vigrously upvote answers with actual code.] [C/C++ code preferred; Assembly okay too.]

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  • Linux C++: how to profile time wasted due to cache misses?

    - by anon
    I know that I can use gprof to benchmark my code. However, I have this problem -- I have a smart pointer that has an extra level of indirection (think of it as a proxy object). As a result, I have this extra layer that effects pretty much all functions, and screws with caching. Is there a way to measure the time my CPU wastes due to cache misses? Thanks!

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  • Seg Fault with malloc'd pointers

    - by anon
    I'm making a thread class to use as a wrapper for pthreads. I have a Queue class to use as a queue, but I'm having trouble with it. It seems to allocate and fill the queue struct fine, but when I try to get the data from it, it Seg. faults. http://pastebin.com/Bquqzxt0 (the printf's are for debugging, both throw seg faults) edit: the queue is stored in a dynamically allocated "struct queueset" array as a pointer to the data and an index for the data

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  • Accessing program information that gdb sees in C++

    - by anon
    I have a program written in C++, on Linux, compiled with -g. When I run it under gdb, I can 1) set breakpoints 2) at those breakpoints, print out variables 3) see the stackframe 4) given a variable that's a structure, print out parts of the structure (i.e. how ddd displays information). Now, given that my program is compiled with "-g" -- is there anyway that I can access this power within my program itself? I.e. given that my program is compiled with "-g", is there some std::vector<string> getStackFrame(); function I can call to get the current stackframe at the current point of execution? Given a pointer to an object and it's type ... can I do std::vector getClassMember(class_name); ? I realize the default answer is "no, C++ doesn't support that level of introspection" -- however, recall I'm on linux, my program is compiled with "-g", and gdb can do it, so clearly the inforamtion is there. Question is: is there some API for accessing it? EDIT: PS Naysers, I'd love to see a reason for closing this question.

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  • Template trick to optimize out allocations

    - by anon
    I have: struct DoubleVec { std::vector<double> data; }; DoubleVec operator+(const DoubleVec& lhs, const DoubleVec& rhs) { DoubleVec ans(lhs.size()); for(int i = 0; i < lhs.size(); ++i) { ans[i] = lhs[i]] + rhs[i]; // assume lhs.size() == rhs.size() } return ans; } DoubleVec someFunc(DoubleVec a, DoubleVec b, DoubleVec c, DoubleVec d) { DoubleVec ans = a + b + c + d; } Now, in the above, the "a + b + c + d" will cause the creation of 3 temporary DoubleVec's -- is there a way to optimize this away with some type of template magic ... i.e. to optimize it down to something equivalent to: DoubleVec ans(a.size()); for(int i = 0; i < ans.size(); i++) ans[i] = a[i] + b[i] + c[i] + d[i]; You can assume all DoubleVec's have the same # of elements. The high level idea is to have do some type of templateied magic on "+", which "delays the computation" until the =, at which point it looks into itself, goes hmm ... I'm just adding thes numbers, and syntheizes a[i] + b[i] + c[i] + d[i] ... instead of all the temporaries. Thanks!

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  • Does Compressed Sensing bring anything new to data Compression?

    - by anon
    Compressed sensing is great for situations where capturing data is expensive (either in energy or time), and thus less samples can now be taken. However, in situations like image compression, given that the data is already on the computer -- does compressed sensing offer anything? For example, would it offer better data compression? Would it result in better image search?... (Note: If you don't know what the field of Compressed Sensing is, please do not respond.)

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  • c++ volatile multithreading variables

    - by anon
    I'm writing a C++ app. I have a class variable that more than one thread is writing to. In C++, anything that can be modified without the compiler "realizing" that it's being changed needs to be marked volatile right? So if my code is multi threaded, and one thread may write to a var while another reads from it, do I need to mark the var volaltile? [I don't have a race condition since I'm relying on writes to ints being atomic] Thanks!

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  • Trace large C++ code base?

    - by anon
    Problem: I have just inherited this 200K LOC source code base. There's only a small part of it I need (and I want to rip all else out). What I would like to do is to be able to: 1) run the program a few times 2) have something (here's where you come in) record which lines of code gets executed 3) then rip out all the irrelevant lines of code I realize this has "problems" in the forms of "different args will take different paths"; but for my needs, it's very specific, and I just want something ot get me started on the right line of for ripping stuff out (I'll fine tune those special cases later). Thanks!

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  • interactive lua prompt in opengl application

    - by anon
    Okay, so when I run lua, I get something like: lua Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio > Now, I want a prompt like this, 1) in a GUI application I've written. My GUI application can provide functions like: get_input_from_screen(); and write_this_crap_out_to_screen(); and more functions I can write as necessary I also know how to embed a lua interpreter in my C++ code (short tutorial on the web) What I don't know .. is how to connect the input/output of a lua interpreter with my GUI stuff. Any help/links apreciated. Thanks!

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  • Is there anyway to write the following as a C++ macro?

    - by anon
    my_macro << 1 << "hello world" << blah->getValue() << std::endl; should expand into: std::ostringstream oss; oss << 1 << "hello world" << blah->getValue() << std::endl; ThreadSafeLogging(oss.str()); Thanks! EDIT: the accepted answer is awesome. Can we upvote 8 more times and win this responder a badge? (The answer only needs 6 more upvotes). 4 more votes to go from 21 to 25. 3 more. :-) Victory. :-)

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  • C++ compile time purity checks?

    - by anon
    Is it possible to specify compile time "purity" checks in C++? I.e.: this function does not read from anything other than it's arguments this function does not write to anything; it only returns the return value

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  • Vim, vimgrep, and file caching

    - by anon
    My entire source code base is < 20MB. I want it all loaded in memory in the background. So that when I do vimgrep */.cpp */.cxx */.hpp , it doesn't ahve to do file IO since vim has loaded all the files into memory already. How can I achieve this? Thakns!

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  • Explanation of output

    - by Anon
    My program class Building { Building() { System.out.print("b "); } Building(String name) { this(); System.out.print("bn " + name); } }; public class House extends Building { House() { System.out.print("h "); // this is line# 1 } House(String name) { this(); // This is line#2 System.out.print("hn " + name); } public static void main(String[] args) { new House("x "); } } We know that compiler will write a call to super() as the first line in the child class's constructor. Therefore should not the output be: b (call from compiler written call to super(), before line#2 b (again from compiler written call to super(),before line#1 ) h hn x But the output is b h hn x Why is that?

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  • Pass a variable to new page

    - by Anon
    I am trying to pass a variable from one page, load another and enter that information. something Like this: When 127.0.0.1/test.html&ID=1234 location.href = "127.0.0.1/newpage.html" if (location.href == newpage.html){ var e = document.GetElementById("Loginbx"); e.Value = ID } I don't have access to modify 127.0.0.1/test.html nor newpage.html but would like to pass variables to them from another. Is this possible?

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  • Sorting a 2 dimensional array on multiple columns

    - by Anon
    I need to sort a 2 dimensional array of doubles on multiple columns using either C or C++. Could someone point me to the algorithm that I should use or an existing library (perhaps boost?) that has this functionality? I have a feeling that writing a recursive function may be the way to go but I am too lazy to write out the algorithm or implement it myself if it has been done elsewhere. :-) Thanks

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  • C++ Variable declarable in function body, but not class member?

    - by anon
    I want to create a C++ class with the following type: It can be declared inside of a function. It can be declared inside of a member function. It can not be declared as a class member. The use of this: think "Root" objects for a GC. Is this possible in C++? In particular, I'm using g++. Willing to switch to clang. Either templates or macro solution fine. Thanks!

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  • InfoPath Getting SharePoint Group Information

    - by anon
    I have an InfoPath form embedded in an aspx page on a SharePoint site. How do I bind the SharePoint user groups to a drop-down list on my form? What I've tried so far is to create a data connection to a web service (method GetGroupCollectionFromWeb) to pull the data. Next, I open the list box properties, select "Look up values from an external data source", select the data source, assign the entries, and I get the following error: "You must select a repeating group or field." What I don't understand is that since the method I am calling is called GetGroupCollectionFromWeb, isn't the return value a collection? And aren't collections repeating by definition? What am I missing, and is there a workaround? Thank you.

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  • fastest way to copy a table in mysql

    - by Anon
    which one is the fastest way to completely copy a table on mysql ? CREATE TABLE copy LIKE original; INSERT INTO copy SELECT * FROM original; or CREATE TABLE copy SELECT * FROM original; ALTER TABLE copy ADD PRIMARY KEY (id); or theres another way ? PS. can't use command-line tools like mysqldump, must be on-the-fly.

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  • lua jump to right line

    - by anon
    I have a makefile that looks like: default: lua blah.lua Now, in vim, I type ":make" There's an error in my lua code; it gives a file name + line number. I would like vim to jump to the right file/line. How do I make this happen? Thanks!

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  • c++ figuring out memory layout of members programatically

    - by anon
    Suppose in one program, I'm given: class Foo { int x; double y; char z; }; class Bar { Foo f1; int t; Foo f2; }; int main() { Bar b; bar.f1.z = 'h'; bar.f2.z = 'w'; ... some crap setting value of b; FILE *f = fopen("dump", "wb"); // c-style file fwrite(&b, sizeof(Bar), 1, f); } Suppose in another program, I have: int main() { File *f = fopen("dump", "rb"); std::string Foo = "int x; double y; char z;"; std::string Bar = "Foo f1; int t; Foo f2;"; // now, given this is it possible to read out // the value of bar.f1.z and bar.f2.z set earlier? } WHat I'm asking is: given I have the types of a class, can I figure out how C++ lays it out?

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