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Cannot read correct file size

This is a discussion on Cannot read correct file size within the C Programming forums, part of the General Programming Boards category; For some reason whenever I read a file it always adds garbage add the end. I can't figure out why. ...

  1. #1
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    Cannot read correct file size

    For some reason whenever I read a file it always adds garbage add the end. I can't figure out why.

    Code:
    fseek(f, 0, SEEK_END);
    long s = ftell(f);
    rewind(f);
    fbuffer = malloc(s);
    fread(fbuffer, 1, s, f);
    fclose(f);
    Always the "s" is too large.

    Can anyone tell me why or how to correctly read files.

  2. #2
    - - - - - - - - oogabooga's Avatar
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    What OS are you using?
    How did you open the file?
    By how much is the file size off?
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

  3. #3
    Registered User
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    Windows XP/7.

    Its a regular text file so "f = fopen("textfile.txt", "r");".

    Its always off by 1-7 maybe 1-10bytes.

  4. #4
    ATH0 quzah's Avatar
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    Like by maybe 1 to 7 carriage returns worth? Don't fseek text files.


    Quzah.
    Hope is the first step on the road to disappointment.

  5. #5
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    It still should work properly.

    And if I don't use it, what else will I use to read it correct?

  6. #6
    Bit Fiddler
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    Use stat.

  7. #7
    a_capitalist_story
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    Your buffer variable is not null-terminated, so if you're trying to print it/treat it as a string, then there are your extra characters...you're printing random data until a '\0' is found in memory. Don't forget to malloc enough space for that null-terminator you need.

  8. #8
    - - - - - - - - oogabooga's Avatar
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    This is a pathetically sad thing about windows. Each line in a text file actually ends with \r\n. But that is translated to just \n when it's read in text mode. So you will have one extra byte per line.

    The fact that you're malloc'ing a few extra bytes is not a big problem. The problem is with properly terminating the buffer. To do so you could use the return value of fread.

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    int main(void) {
        char*  fbuffer;
        FILE*  f;
        long   s;
        size_t st;
    
        f = fopen("atextfile.txt", "r");
        fseek(f, 0, SEEK_END);
        s = ftell(f);
    
        fbuffer = malloc(s + 1);
    
        rewind(f);
        st = fread(fbuffer, 1, s, f);
        fbuffer[st] = 0;
        fclose(f);
    
        printf("s=%ld\nst=%u\nText:\n%s", s, st, fbuffer);
    
        return 0;
    }
    memcpy likes this.
    The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss

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