reading digits from a text file

This is a discussion on reading digits from a text file within the C Programming forums, part of the General Programming Boards category; Hello, I'm learning c myself (not c++, I'm trying not to use objects) I have have a bunch of text ...

  1. #1
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    reading digits from a text file

    Hello,

    I'm learning c myself (not c++, I'm trying not to use objects)

    I have have a bunch of text files (created by a perl program)

    They contain a bunch of letters and random numbers from 0 to 9
    I'm only interested in the numbers and nothing else

    here's and example of the contents (i just made it up)

    5 7 2 4 6
    0 2 E D
    0 A D E
    6 D D
    7 D K
    5 F

    How do I go about loading just the numbers into an array?
    so I want an array that that has

    5 7 2 4 6 0 2 0 6 7 5

    Basically the above is an example, there can be more per line and more lines, but I just need the numbers.

    Any examples/help appricated

  2. #2
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    Assuming that this is for a school assignment, I'll try to provide the proper kind of assistance.

    First of all, think of how large you should make your array when the program starts. Once it's made, it can't be changed unless you make a new one and copy contents over.

    To read the characters from the file, have a look at the fscanf manpage.

    There is a function that you will find very useful for this assignment in ctype.h.

    As far as how to easily navigate your array or file, have a look in your text book's index under "pointer arithmetic".

    Hope this helps,

    ~arker

  3. #3
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    Thanks for your input.

    lol not for a school assignment, bit to old for school lol. Just picked up a c programming book and giving it a shot

  4. #4
    and the hat of int overfl Salem's Avatar
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    Read each character from the file, then use the isdigit() function in ctype.h to determine whether its a numeric char
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  5. #5
    Been here, done that.
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    Originally posted by Salem
    Read each character from the file, using fgetc() then use the isdigit() function in ctype.h to determine whether its a numeric char
    ... or learn to compare the values by hand, testing if they are between '0' and '9'. I'd suggest for practice write your program both ways.
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