Thread: pointers searching through a file

  1. #1
    Registered User
    Join Date
    Oct 2012

    pointers searching through a file

    hi guys

    say you have a extern file with numbers from 0-20. so it contains

    the program's supposed to give all numbers greater than the number given on keyboard.

    my file's called List however. so the sketch would look like this:

    FILE *pfile;
    pfile=fopen("C:\user\list.txt", "r+");
    if(pfile != NULL){
    .......  //my problem
     //it'd better follow with a else command in case the file doesn't work right
    now somehow I should run the pfile pointer through the data in the "list" file so it could find the one that are greater than the number given via scanf....

    and I can't figure how exactly...would running this work?


    I'd be grateful for any hint....
    Last edited by Aitra; 01-19-2013 at 09:32 AM.

  2. #2
    SAMARAS std10093's Avatar
    Join Date
    Jan 2011
    Nice, France

    Check the return value for EOF.

    Once you read a number, compare it with the number from keyboard. If it is ok, then print it. If not do nothing. Go the next number in the file ( a loop ).

    For the else part, have a message informing the user that the file could not open and exit with return -1;
    Code - functions and small libraries I use

    It’s 2014 and I still use printf() for debugging.

    "Programs must be written for people to read, and only incidentally for machines to execute. " —Harold Abelson

  3. #3
    Registered User
    Join Date
    Sep 2006
    If pfile==NULL, there's no need to close fclose(pfile), because it was never opened. Print the file didn't open message\n and exit or return.

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