write an array of unspecified size to a file

This is a discussion on write an array of unspecified size to a file within the C++ Programming forums, part of the General Programming Boards category; how do i loop until this is done? the way it is written currently, it only writes the first 512 ...

  1. #1
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    write an array of unspecified size to a file

    how do i loop until this is done?
    the way it is written currently, it only writes the first 512 characters. how can i make it loop until it writes the whole file? i think i need some kind of loop in my writer code section where i have set up the while loop that i dont know how to fill in. any ideas?




    //reader
    Code:
    #include <iostream>
    #include <fstream>
    using namespace std;
    
    int main(int argc, char *argv[])
    {
            cout << "in reader" << endl;
            char readbuffer[512];
            int ipipe = atoi(argv[2]);
            ifstream ifs(argv[1]);
    
            while (!ifs.eof())
            {
                    ifs.read(readbuffer, sizeof(readbuffer));
                    write(ipipe, readbuffer, ifs.gcount());
            }
    
            close(ipipe);
    
    
            return 0;
    }

    //writer
    Code:
    #include <iostream>
    #include <fstream>
    using namespace std;
    
    int main(int argc, char *argv[])
    {
            cout << "in writer" << endl;
            char writebuffer[512];
            int rc;
            int ipipe = atoi(argv[2]);
            ofstream ofs(argv[1]);
    
    
            while (?)
            {
                rc = read(ipipe, writebuffer, sizeof(writebuffer));
                ofs.write(writebuffer, rc);
            }
    
            close(ipipe);
    
    
    
            return 0;
    }

  2. #2
    and the hat of wrongness Salem's Avatar
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    while read() returns >0 result.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  3. #3
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    Quote Originally Posted by Salem View Post
    while read() returns >0 result.
    i tried

    Code:
    do
    {
          //do code
    }while (rc>0);
    but my output file was overwritten with nothingness which means it must have written past the end of the file. how can i correct this?

  4. #4
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    nvm, i got it. you put me on the right track though, thank you

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