file names, reading files

Discussion in 'C++' started by Miner Jeff, Apr 14, 2008.

  1. Miner Jeff

    Miner Jeff Guest

    Hello, I have a basic question about reading files.

    I have several data files where the filenames are identical except for
    a short (3 character) prefix. I inherited this code and the person who
    developed it was making a duplicate of each file and then deleting the
    prefix on the copied file so the following statement could read a
    generic "filename":



    ifstream inFile("filename", ios::eek:ut);


    There are 20 files so I'd like to avoid this manual operation each
    time I run the program.

    I want to add a prefix to the string "filename" before reading the
    file so I don't have to go manually create the file before running the
    program. Each time I run the program, I want the operator to enter
    the Prefix and then have the program combine the prefix with
    "filename" and read the file.

    It's not often I get to test code on my target system so I'm asking
    for opinions on the following approach. Part of the following code was
    gleaned from a posting by Ralph McArdell at:
    http://en.allexperts.com/q/C-1040/changing-name-text-file.htm . I'm
    only reading the file once during program execution so I don't think I
    need to rewind os as was shown in the referenced posting.


    ostringstream os;

    char prefix[3]="";
    cin>>prefix;
    os << prefix << "filename";
    ifstream infile( os.str().c_str(), ios::eek:ut );



    I appreciate any comments and suggestions. If there's a way to
    concatenate the operator-entered 'prefix' with 'filename' without
    using os, that's what I'd prefer.


    Thanks,

    Jeffrey Bledsoe
     
    Miner Jeff, Apr 14, 2008
    #1
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  2. Miner Jeff

    Miner Jeff Guest

    On Apr 14, 11:48 am, "Alf P. Steinbach" <> wrote:
    > * Miner Jeff:
    >  > [how to concatenate strings]
    >
    > #include <string>
    > #include ...
    >
    > int main()
    > {
    >      using namespace std;
    >      string const basicFilename = "pasta.food";
    >      string prefix;
    >
    >      getline( cin, prefix );   // Error checking omitted for brevity.
    >      string const fullFilename = prefix + basicFilename;
    >
    >      ifstream infile( fullFilename.c_str() );  // ios::eek:ut would be wrong here.
    >
    > }
    >
    > Cheers, & hth.,
    >
    > - Alf


    Thanks Alf. I'll try it tomorrow during my scheduled test time.

    Jeff
     
    Miner Jeff, Apr 14, 2008
    #2
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  3. Miner Jeff

    Miner Jeff Guest

    On Apr 14, 11:48 am, "Alf P. Steinbach" <> wrote:
    > * Miner Jeff:
    >  > [how to concatenate strings]
    >
    > #include <string>
    > #include ...
    >
    > int main()
    > {
    >      using namespace std;
    >      string const basicFilename = "pasta.food";
    >      string prefix;
    >
    >      getline( cin, prefix );   // Error checking omitted for brevity.
    >      string const fullFilename = prefix + basicFilename;
    >
    >      ifstream infile( fullFilename.c_str() );  // ios::eek:ut would be wrong here.
    >
    > }
    >
    > Cheers, & hth.,
    >
    > - Alf


    It worked. I decided to create a folder for the files so I created
    another string constant (for the directory) and concatenated it with
    the other 2 strings. Thanks for the help.

    BTW, I was surprised to see, judging from the subject lines, a lot of
    off-subject 'trash' on this site today. I didn't notice anything of
    that nature yesterday. I assume the discussion manager cleans it up
    once in a while. Correct?

    Thanks again,

    Jeff
     
    Miner Jeff, Apr 15, 2008
    #3
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