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  • (C++) Loading a file into a vector

    - by Alden
    This is probably a simple question, however I am new to C++ and I cannot figure this out. I am trying to load a binary file and load each byte to a vector. This works fine with a small file, but when I try to read larger than 410 bytes the program crashes and says: This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. I am using code::blocks on windows. This is the code: #include <iostream> #include <fstream> #include <vector> using namespace std; int main() { std::vector<char> vec; std::ifstream file; file.exceptions( std::ifstream::badbit | std::ifstream::failbit | std::ifstream::eofbit); file.open("file.bin"); file.seekg(0, std::ios::end); std::streampos length(file.tellg()); if (length) { file.seekg(0, std::ios::beg); vec.resize(static_cast<std::size_t>(length)); file.read(&vec.front(), static_cast<std::size_t>(length)); } int firstChar = static_cast<unsigned char>(vec[0]); cout << firstChar <<endl; return 0; } Thank you for your help!

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  • Write file in sub-directory in Android

    - by Davide Vosti
    I'm trying to save a file in a subdirectory in Android 1.5. I can successfully create a directory using _context.GetFileStreamPath("foo").mkdir(); (_context is the Activity where I start the execution of saving the file) but then if I try to create a file in foo/ by _context.GetFileStreamPath("foo/bar.txt"); I get a exception saying I can't have directory separator in a file name ("/"). I'm missing something of working with files in Android... I thought I could use the standard Java classes but they don't seem to work... I searched the Android documentation but I couldn't fine example and google is not helping me too... I'm asking the wrong question (to google)... Can you help me out with this? Thank you!

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  • Writing different structs to a file in C++? [on hold]

    - by user58053
    I need a way to write structures of three different kinds to a binary file, which later has to be searched. (As in, for example, struct A has two fields, an int and a char; struct B has int and a long; I need to output all structures whose int equals the one given from keyboard). I understand how to write structs of the same kind to a file and how to search them, but here I am just lost, best thing I came up with is declaring a struct containing all possibly needed fields and leaving the ones I don't need empty, but it really feels wrong, there HAS to be a better way to do that. I've read about binary files and could not find anything relevant, most examples and tutorials deal with writing one data type. Could anyone point me in the right direction? EDIT: I am looking for what @Jerry_coffin called database mode, and will probably use one of the existing database systems for that, best way to go, probably. Thank you everybody for the suggestions

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  • Prompt with UAC when user doesn't have access to copy a file

    - by Will Eddins
    In my application, if the user saves a file to a folder they don't have permissions for, File.Copy will fail. An example is saving a document to the C:\ root. Instead of denying access, I'd like to prompt the user to elevate permissions with a UAC prompt, but only for this save function (not for the entire application). Is there a way to do this?

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  • Good C string libary

    - by chamakits
    Hello all. I recently got inspired to start up a project I've been wanting to code for a while. I want to do it in C, because memory handling is key this application. I was searching around for a good implementation of strings in C, since I know me doing it myself could lead to some messy buffer overflows, and I expect to be dealing with a fairly big amount of strings. I found this article which gives details on each, but they each seem like they have a good amount of cons going for them (don't get me wrong, this article is EXTREMELY helpful, but it still worries me that even if I were to choose one of those, I wouldn't be using the best I can get). I also don't know how up to date the article is, hence my current plea. What I'm looking for is something that may hold a large amount of characters, and simplifies the process of searching through the string. If it allows me to tokenize the string in any way, even better. Also, it should have some pretty good I/O performance. Printing, and formatted printing isn't quite a top priority. I know I shouldn't expect a library to do all the work for me, but was just wandering if there was a well documented string function out there that could save me some time and some work. Any help is greatly appreciated. Thanks in advance! EDIT: I was asked about the license I prefer. Any sort of open source license will do, but preferably GPL (v2 or v3). EDIt2: I found betterString (bstring) library and it looks pretty good. Good documentation, small yet versatile amount of functions, and easy to mix with c strings. Anyone have any good or bad stories about it? The only downside I've read about it is that it lacks Unicode (again, read about this, haven't seen it face to face just yet), but everything else seems pretty good. EDIT3: Also, preferable that its pure C.

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  • writing structs and classes to disk

    - by Phenom
    The following function writes a struct to a file. int btwrite(short rrn, BTPAGE *page_ptr) { long addr; addr = (long) rrn * (long) PAGESIZE + HEADERSIZE; lseek(btfd, addr, 0); return (write(btfd, page_ptr, PAGESIZE)); } The following is the struct. typedef struct { short keycount; /* number of keys in page */ int key[MAXKEYS]; /* the actual keys */ int value[MAXKEYS]; /* the actual values */ short child[MAXKEYS+1]; /* ptrs to rrns of descendants */ } BTPAGE; What would happen if I changed the struct to a class, would it still work the same? If I added class functions, would the size it takes up on disk increase?

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  • How do i have a jar communicate with another jar

    - by ObviousComplexities
    Ok so i have 2 jars (Console, Core) 1st-Console) receives user input 2nd-Core) processes the input and gives an output i'm trying to have the two "Communicate" with each other by exchanging input and output now i have tried writing to a file to communicate when i ran into the problem of "Notifying" the other that there is input to receive and output to give i'm a bit new to this ideal so if its an easy function, please don't criticize.

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  • How to replace same text in a text file

    - by user1688220
    i created a c# windows login form and i am saving username or password to a text file but every time i use same username or password that i have saved before it takes new place in that text file. But What i want is to replace the same username or password that is already saved in that text file. this is my code: private void button1_Click(object sender, EventArgs e) { try { FileStream fs = new FileStream("data.txt", FileMode.Append, FileAccess.Write); StreamWriter sw = new StreamWriter(fs); sw.Write("Email ID: "); sw.WriteLine(textBox1.Text); sw.Write("Password: "); sw.Write(textBox2.Text); sw.WriteLine(); sw.WriteLine(); sw.Flush(); sw.Close(); fs.Close(); } catch (Exception) { MessageBox.Show("Error", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); this.Close(); } MessageBox.Show("DONE", "Done", MessageBoxButtons.OK, MessageBoxIcon.Information); textBox1.Clear(); textBox2.Clear(); }

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  • Operator Overloading << in c++

    - by thlgood
    I'm a fresh man in C++. I write this simple program to practice Overlaoding. This is my code: #include <iostream> #include <string> using namespace std; class sex_t { private: char __sex__; public: sex_t(char sex_v = 'M'):__sex__(sex_v) { if (sex_v != 'M' && sex_v != 'F') { cerr << "Sex type error!" << sex_v << endl; __sex__ = 'M'; } } const ostream& operator << (const ostream& stream) { if (__sex__ == 'M') cout << "Male"; else cout << "Female"; return stream; } }; int main(int argc, char *argv[]) { sex_t me('M'); cout << me << endl; return 0; } When I compiler it, It print a lots of error message: The error message was in a mess. It's too hard for me to found useful message sex.cpp: ???‘int main(int, char**)’?: sex.cpp:32:10: ??: ‘operator<<’?‘std::cout << me’????? sex.cpp:32:10: ??: ???: /usr/include/c++/4.6/ostream:110:7: ??: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostre

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  • Using FILE_FLAG_NO_BUFFERING will return noticeable speed gain?

    - by 9dan
    Recently noticed detail description of FILE_FLAG_NO_BUFFERING flag in MSDN, and read several Google search results about unbuffered I/O in Windows. http://msdn.microsoft.com/en-us/library/aa363858(v=vs.85).aspx I wondering now, is it really important to consider unbuffered option in file I/O programming? Because many programs use plain old C stream I/O or C++ iostream, I didn't gave any attention to FILE_FLAG_NO_BUFFERING flag before. Let's say we are developing photo explorer program like Picasa. If we implement unbuffered I/O, could thumbnail display speed show noticeable difference in ordinary users?

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  • related to java file handling.

    - by sadia
    In Java how can I take the data of my file on my display screen? I want to use data in my file and also want that data to be displayed on my output screen when I execute my program. Can any body please help by providing me such example in Java language. Thank you!

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  • explain this macro

    - by deostroll
    #define __T(x) L ## x Found in code from one of the MFC source header file. It is mostly used for converting strings to ........ (I don't know what). If I am correct it converts strings to LPCTSTR...don't know what that type is either... I can't seem to convert char* into LPCTSTR. While MFC file handling, the following code will always return error while trying to open the file... char* filepath = "C:\\Program Files\\Microsoft Office\\Office12\\BITMAPS\\STYLES\\GLOBE.WMF"; if( !file.Open((LPCTSTR)filepath , CFile::modeRead, &fexp) ) { fexp.ReportError(); return 1; } But instead if I wrote it this way, it doesn't give error: if( !file.Open( _T("C:\\Program Files\\Microsoft Office\\Office12\\BITMAPS\\STYLES\\GLOBE.WMF") , CFile::modeRead, &fexp) ) { fexp.ReportError(); return 1; } I am looking at passing a variable as the first argument to the CFile::Open() method.

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  • Split a binary file into chunks c++

    - by L4nce0
    I've been bashing my head against trying to first divide up a file into chunks, for the purpose of sending over sockets. I can read / write a file easily without splitting it into chunks. The code below runs, works, kinda. It will write a textfile and has a garbage character. Which if this was just for txt, no problem. Jpegs aren't working with said garbage. Been at it for a few days, so I've done my research, and it's time to get some help. I do want to stick strictly to binary readers, as this need to handle any file. I've seen a lot of slick examples out there. (none of them worked for me with jpgs) Mostly something along the lines of while(file)... I subscribe to the, if you know the size, use a for-loop, not a while-loop camp. Thank you for the help!! vector<char*> readFile(const char* fn){ vector<char*> v; ifstream::pos_type size; char * memblock; ifstream file; file.open(fn,ios::in|ios::binary|ios::ate); if (file.is_open()) { size = fileS(fn); file.seekg (0, ios::beg); int bs = size/3; // arbitrary. Actual program will use the socket send size int ws = 0; int i = 0; for(i = 0; i < size; i+=bs){ if(i+bs > size) ws = size%bs; else ws = bs; memblock = new char [ws]; file.read (memblock, ws); v.push_back(memblock); } } else{ exit(-4); } return v; } int main(int argc, char **argv) { vector<char*> v = readFile("foo.txt"); ofstream myFile ("bar.txt", ios::out | ios::binary); for(vector<char*>::iterator it = v.begin(); it!=v.end(); ++it ){ myFile.write(*it,strlen(*it)); } }

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  • How to switch data pins on/off on parallel port?

    - by Matt
    I want to simply switch certain data pins on and off, so that they can control a set of relays. I'm not asking about the hardware bit (should be easy), but I don't know where to begin writing the software. I don't want a high level library that can send bytes to a device - I literally want to switch on/off certain pins. I'm running Linux and I want to do this in Java, so would I just need a library? It would be nice if the library has good documentation and is easy to use, but if not then a short example code will help me get started.

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  • Generic file container for quick read of data

    - by DreamCodeR
    Since there are some major privacy issues with alot of social networking sites I am trying to think about alternatives. One is to let the user keep all the information stored in some kind of file container. Now, I haven't found a single type of container that can hold "generic" information. Only for audio/video. What I want is a container that can be read by PHP with some kind of index file that lists up the users pictures in a image/ directory in the container, FOAF files (or some alternative XML-file describing users information and friends, etc.). My thoughts was to let the user keep all their information and data stored in a container that can be imported/exported and deleted from my server (the prototype social networking site I am trying to create), and then uploaded to another site that might use the same format (not that I think that will ever happen, but the user still keeps all their pictures, data, comments, messages, etc). The only thing I have come up with yet is to create a tar archive with the Archive_tar library which extracts and creates Tar-archives with an index-file describing which files are holding the messages (there might be several so each file won't be so large), what pictures are in the image/ folder and what are their names and what comments they have gotten etc. Maybe also the permissions for viewing each type of content. Does there exist any generic file format of a container that I can use to keep all this information in one file with a tree-like index file? Or must i try and create something like this myself?

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  • Perl, redirect stdout to file

    - by Mike
    I'm looking for an example of redirecting stdout to a file using Perl. I'm doing a fairly straightforward fork/exec tool, and I want to redirect the child's output to a file instead of the parents stdout. Is there an equivilant of dup2() I should use? I can't seem to find it

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  • Enter custom file name to be read ?

    - by ZaZu
    Hello, I want to allow users to type the name of any .txt file to be read/written. This is my code : printf("Enter .txt file name\n"); scanf("%s",&fname); FILE *inputf; inputf=fopen(&fname,"w"); Problem is this method does not work (having &fname) as a parameter. I can imagine its because C needs "filename.txt" for it work ... even if I enter for example : "custom.txt", the program returns an error of "Storage block not big enough for this operation" What is the correct method to accomplish this ? Im using C and im pretty much using basic commands .. (not too advanced) Thanks alot !!!

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  • How to open a text file that's not in the same folder?

    - by nunos
    Since C it's not a language I am used to program with, I don't know how to do this. I have a project folder where I have all the .c and .h files and a conf folder under which there is a config.txt file to read. How can I open that? FILE* fp = fopen("/conf/config.txt"); if (fp != NULL) { //do stuff } else printf("couldn't open file\n"); I keep getting the error message. Why? Thanks.

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  • Can you call Directory.GetFiles() with multiple filters?

    - by Jason Z
    I am trying to use the Directory.GetFiles() method to retrieve a list of files of multiple types, such as mp3's and jpg's. I have tried both of the following with no luck: Directory.GetFiles("C:\\path", "*.mp3|*.jpg", SearchOption.AllDirectories); Directory.GetFiles("C:\\path", "*.mp3;*.jpg", SearchOption.AllDirectories); Is there a way to do this in one call?

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  • Why is this writing part of the text to a new line? (Python)

    - by whatsherface
    I'm adding some new bits to one of the lines in a text file and then writing it along with the rest of the lines in the file to a new file. Referring to the if statement, I that to be all on the same line: x = 13.55553e9 y = 14.55553e9 z = 15.55553e9 infname = 'afilename' outfname = 'anotherone' oldfile = open(infname) lnum=1 for line in oldfile: if (lnum==18): line = "{0:.2e}".format(x)+' '+line+' '+"{0:.2e}".format(y)+' '+ {0:.2e}".format(z) newfile = open(outfname,'w') newfile.write(line) lnum=lnum+1 oldfile.close() newfile.close() but y and z are being written on the line below the rest of it. What am I missing here?

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  • Creating a file path in C#

    - by Jason
    So I'm trying to create a path in C#. I use Environment.Machinename and store it a variable serverName. Then I create another string variable and have some other path extension in there. Here is my code so far: string serverName = Environment.MachineName; string folderName = "\\AlarmLogger"; No matter what I do I can't seem to obtain only one backslash prior to AlarmLogger. Any ideas how I can specify a path in C#? Edit: I'm wondering if my code doesn't seem to want to paste correctly. Anyways when i paste it I only see one backslash but my code has two. Because of the escape character sequence. But something like string test = @"\" + serverName + folderName doesn't seem to want to work for me.

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