Reading two values from a file as one value?

This is a discussion on Reading two values from a file as one value? within the C Programming forums, part of the General Programming Boards category; After about two or more hours of experimenting and going crazy trying to find an answer, I've decided to bring ...

  1. #1
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    Reading two values from a file as one value?

    After about two or more hours of experimenting and going crazy trying to find an answer, I've decided to bring the problem here, where there are many people that know what they're doing.

    I'm writing a C program to open a file and read bytes on each line, formatting them along the way.

    Code:
    #include <stdio.h>
    
    int main()
    {
    FILE *modeldata1, *modeldata2;
    char modeldata1choice[30],modeldata2choice[30];
    
    printf("Model to convert: ");
    gets(modeldata1choice);
    printf("Save converted file as: ");
    gets(modeldata2choice);
    
    }
    That is generally what I have so far (I'm not including the loops and some other things as to not take up too much space).

    > One loop operates on the file-size of "modeldata1." How could I get the total size of the file in hex bytes?

    > The other loop will need to read two bytes at a time into their corresponding variables.

    float xcoord,ycoord,zcoord;

    XX XX YY YY ZZ ZZ

    I've tried fgets and fgetc, but they don't seem to be working out. The fgets function will read two bytes for me, but it reads them in a string format that shows the wrong values when in hex.

    Hopefully I didn't make this very confusing.

  2. #2
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    Post up an example of input and the output that you want. Your description leaves questions.

    Focus on the data types, and not on how they're being represented.

  3. #3
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    Example:

    Input = File to get data from.

    Let's say that the file is only one line. The first six bytes would be grabbed, in sets of two.

    XX XX YY YY ZZ ZZ

    For example, 00 00 FF 7F 50 00. (00 00 are read as one value. FF 7F are read as one value. 50 00 are read as one value.)

    Output is formatted like so (basically, those values, but in decimal):
    v 0 65407 20480

  4. #4
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    Code:
    int a[6];
    fscanf(fptr, "%x %x %x %x %x %x", &a[0], &a[1], &a[2], &a[3], &a[4], &a[5]);
    printf("v %d %d %d\n", (a[0] << 8) | a[1], (a[2] << 8) | a[3], (a[4] << 8) | a[5]);
    (not syntax checked)

  5. #5
    Programming Wraith GReaper's Avatar
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    Advice: To do what you want, drop formatted input and directly grab each 4 bytes. Open your file in "rb" state and call "fwrite".
    Devoted my life to programming...

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