CODEWITHSUNDEEP
c
Hiroshi Nakamura
Hiroshi Nakamura

Reputation: 31

How to read text file in C?

I'm trying to read a txt file containing strings of 1s and 0s and print it out in the manner below. I tried my code a couple of months ago and it worked fine in reading the text file. Now when I tried it, it outputs something really strange. Also I tried changing the directory of the file to a non-existant file but it still outputs the same thing when it should've quit the program immediately. Please help!

The content of txt file:-

10000001
01110111
01111111
01111010
01111010
01110111

Expected output:-

data_in<=24'b10000001;
#10000;

Real output:-

data_in<=24'b(some weird symbol that changes everytime I recompile);
#10000;

My code:-

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main (int argc, char *argv[])
{
    int i, j;
    j = 0;
    char words[50];
    FILE *fp;
    fp = fopen (argv[1], "r");

    if (fp == NULL) {
        printf ("Can't open file\n");
    }

    while (feof (fp) == 0) {
        fscanf (fp, "%s", words);
        printf ("data_in<=24'b%s\n", words);
        printf ("#10000\n");
    }

    fclose (fp);
    system ("PAUSE");
    return 0;
}

The input argument is the following:-

"C:\Users\Beanz\Documents\MATLAB\football frame\frame1.txt"

Upvotes: 2

Views: 3254

Answers (2)

user3629249
user3629249

Reputation: 16540

Remember that 'feof()' is only set AFTER trying to read PAST the end of the file, not when at the end of the file.

So the final iteration through the loop will try to read/process data that contains trash or prior contents.

Always check the returned value from 'fscanf()' before trying to use the associated data.

strongly suggest

eliminate the call to feof() and use the fscanf() to control the loop

Upvotes: 1

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

Read each line one by one with getline(3) -if available- or with fgets (you'll then need a large enough line buffer, at least 256 bytes), then parse each line buffer appropriately, using sscanf (the %n might be useful, and you should test the scanned item count result of sscanf) or other functions (e.g. strtok, strtol, etc...)

Upvotes: 1

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