Thread: Trouble counting digits

Code:

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <fcntl.h>
#include <sys/stat.h>

int main(int argc, char** argv) {

    FILE *textfile;
    int max_chars = 1000;
    int chars = 0;
    int digits = 0;
    char contents[max_chars];
    char c;

    textfile = fopen("file.txt", "r");

     if (textfile == NULL) {
        printf("Cannot open file.");
        exit(8);
    }

    while ((c = fgetc(textfile)) != EOF) {
        chars++;
    }

    fread(contents,max_chars,1,textfile);

    printf("Characters in text file: %d\n", chars);

    for (i = 0; i < chars; i++) {
    if ((contents[i] != '\0') && (contents[i] != '\n') && (contents[i] != '\t')) {

        if isdigit(contents[i]) {
            printf("digit: %c\n",contents[i]);
            digits++;
        }

       }
    }

    printf("Total digits: %d\n", digits);

    fclose(textfile);


    return (EXIT_SUCCESS);
}

file.txt:

July 4th, 1776.

Output:

Characters in text file: 15
digit: 4
Total digits: 1

I'm not understanding why it is only counting the 4 and not the other digits.

Try rewind () before doing fread. You are at the EOF why do you think it will read anything.

Tim S.

Thanks. I knew it had something to do with the fgetc() being at the EOF but I wasn't sure how to go back to the beginning.

Ok so you're only counting digits... why don't you just read it in character by character?
You don't need arrays or buffers or anything fancy, in fact you don't even have to store the file's contents
Just go at it with plain old fgetc() and isdigit()...

Like this...

Code:

// open your file
do 
 { if (isdigit(fgetc(MyFile)))
     digits++;
   characters++;
 } while (c > 0)
// close your file
// print your report

One of the biggest mistakes in programming is the tendency to overthink things to the point of sheer lunacy...
Work the problem out on paper... write down what you need to do step by step.
Now cross out everything you listed that you do not absolutely have to do.
There's your program...

(hint: a good programmer could do this in about 12 lines)

I was going to storing them in an array because I was going to compare all the characters to see if they are the same.

If I want to compare the characters, I would have to store them in an array, right?

Yes if you have additional things to do you may need arrays and such to store the file's contents.

In that case, change gears... open your file, read the whole thing into a character buffer, close your file.
Now you can work on the buffer and forget about the file... count characters, count digits, compare things, whatever you need to do.

Always look for the easy way... It makes things a lot, ummm, easier...

Originally Posted by laserlight

In the specific case of comparing all characters to see if they are the same, you don't need an array. Just read the first character, then as you read the remaining characters, check if they are equal to that first character.

Thanks laze...

Originally Posted by laserlight

In the specific case of comparing all characters to see if they are the same, you don't need an array. Just read the first character, then as you read the remaining characters, check if they are equal to that first character.

I have to count the frequency of each character. Do I need an array then?

What is an array index, and how would I map a character into one?

The values of the characters are stored in contents[]. So by "mapping them to an array index" do you mean I have to store them in another array?

No... mapping refers to how you store them in the array you've already got.
For example: your fread() call already maps them into the array in file order.
Another form of mapping might be to have an array of 26 positins represeinting how many of each letter you read.

However; I would caution you against constantly changing the specifications of your project. Not only will you turn it into a hack job, you'll eventually wear out people's patience. Your best bet is to sit down and decide what you want to do --write a specification-- then post it here so we all know what we're talking about.