Thread: Setting a pointer to file data

  1. #1
    Registered User
    Join Date
    Mar 2005

    Setting a pointer to file data

    I was wondering if there was any way of setting a pointer to the data of a file. I would use:

    ifstream name (argv[1])
    That would open the file, but is there any way to make a variable point to the start of "name". The file is ASCII *.txt file. Also, is there a way to delete characters in a file?

  2. #2
    Registered User Codeplug's Avatar
    Join Date
    Mar 2003
    Welcome to the boards.

    To have a pointer to the files contents, you will have to read the files contents into a buffer. There are many ways to do this. Here's one way to read the entire contents of a file into a dynamically allocated buffer:
    #include <fstream>
    #include <iostream>
    #include <memory>
    using namespace std;
    int main()
        // open the stream as binary so we can get the size of the file
        ifstream f("input.txt", ios::in | ios::binary); 
        if (!f)
            cout << "Failed to open" << endl;
            return 1;
        // get the size of the file
        f.seekg(0, ios::end);
        size_t fsz = f.tellg();
        f.seekg(0, ios::beg);
        // allocate room for the file's contents and a null terminator
        auto_ptr<char> fp_ap(new char[fsz + 1]);
        char *fp = fp_ap.get();
        // read in the whole file, fsz);
        if (!f.good())
            cerr << "Failed to read" << endl;
            return 2;
        // null terminate the entire file contents as a string
        fp[fsz] = 0;
        cout << fp << endl;
        return 0;

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