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last line of file is duplicated using fscanf


last line of file is duplicated using fscanf

By : Will Mc
Date : November 22 2020, 10:56 AM
like below fixes the issue Using feof() like this is wrong.
code :
while (fscanf(hist, "%s %s %s %s %f %f", acR, hdate, htime, dis, &deb, &cre) == 6)
    {
    // Put your code here
    }


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Fscanf or Fgets? Reading a file line after line

Fscanf or Fgets? Reading a file line after line


By : nickhj28
Date : March 29 2020, 07:55 AM
Does that help i have to write a program in C to read a file containing several line of text, each line contains two variables: a number (%f) and a string: , A couple of things.
First, you gotta use fclose().
code :
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main (int argc, char *argv[])
{
    int r, line = 0, found = 0;
    float temp, t_tot = 0;
    char loc[32];

    FILE *fp;
    fp = fopen(argv[1], "r");

    if (fp == NULL)
    {
        printf ("Error opening the file\n\n'");
        exit(EXIT_FAILURE);
    } else {

        if (argc == 3)
        {
            r = fscanf(fp, "%f %s\n", &temp, loc);
            while (r != EOF)
            {
                line++;
                if (r == 2)
                {
                    if(strcmp(argv[2], loc) == 0)
                    {
                        t_tot += temp;
                        found++;
                    }
                }
                else
                    printf ("Error, line %d in wrong format!\n\n", line);
                r = fscanf(fp, "%f %s\n", &temp, loc);
            }
            printf ("The average temperature in %s is: %.1f\n\n", argv[2], (t_tot / found));
        }

    fclose(fp);

    }
}
Traverse FILE line by line using fscanf

Traverse FILE line by line using fscanf


By : Aaron
Date : March 29 2020, 07:55 AM
This might help you I think you need a closing \n in your pattern. I saw the a bunch of scrolling text with the same first line with %[^\n], but with %[^\n]\n I saw the expected output.
However, if the line in the file exceeds that of the buffer, you may run into a problem where your buffer doesn't have enough space. The results
code :
#include <stdio.h>


int main(int argc, char * argv[])
{
    FILE * database;
    char buffer[30];

    database = fopen("test.txt", "r");

    if (NULL == database)
    {
         perror("opening database");
         return (-1);
    }

    while (EOF != fscanf(database, "%[^\n]\n", buffer))
    {
         printf("> %s\n", buffer);
    }

    fclose(database);
    return (0);
}
> 12343456567856789
> zbasdflkjasdfkjklsdafjklas
> zxcvjkleryjkldhfg
> 1234567890123456789012341234
> 12345678901234567890123123asdfjklzxcv;jkl;eqwrtjklkzlcxvjkleqrt41234
*** stack smashing detected ***: ./fscanf terminated                                                                                                                   
Segmentation fault (core dumped)
#include <stdio.h>


int main(int argc, char * argv[])
{
    FILE * database;
    char buffer[30];

    database = fopen("test.txt", "r");

    if (NULL == database)
    {
         perror("opening database");
         return (-1);
    }

    while (EOF != fscanf(database, "%30[^\n]\n", buffer))
    {
         printf("> %s\n", buffer);
    }

    fclose(database);
    return (0);
}
> 12343456567856789
> zbasdflkjasdfkjklsdafjklas
> zxcvjkleryjkldhfg
> 1234567890123456789012341234
> 12345678901234567890123123asdf
> jklzxcv;jkl;eqwrtjklkzlcxvjkle
> qrt41234
12343456567856789
zbasdflkjasdfkjklsdafjklas
zxcvjkleryjkldhfg
1234567890123456789012341234
12345678901234567890123123asdfjklzxcv;jkl;eqwrtjklkzlcxvjkleqrt41234
/* fgets example */
#include <stdio.h>

int main()
{
    FILE * database;
    int res;
    char buffer [100];

    database = fopen(fileName,"r");

    if (NULL == database) {
        perror("opening database file");
        return (-1);
    }

    /* while not end-of-file */
    while (!feof(database)) { 

        /* we expect buffer pointer back if all is well, get out if we don't get it */
        if (buffer != fgets(buffer, 100, database))
            break;

        /* strip /n */
        int len = strlen(buffer);
        if (buffer[len - 1] == '\n')
            buffer[len - 1] = 0;

        printf("ATTEMPT TO: Insert user %s\n\n", buffer); 

        if (insert_Customer(clients, create_Customer(buffer)) < 0)
            printf("\nERROR: Failed to insert and create customer %s\n", buffer); 
        else
            printf("\nSUCCESS: Inserted Customer %s\n\n", buffer);
    }

    /* a little clean-up */
    fclose(database);

    return (0);
}
Using fscanf to read line by line from input file

Using fscanf to read line by line from input file


By : user2691348
Date : March 29 2020, 07:55 AM
should help you out If you are still stuck, a short example may help. Looking at your attempted format string, e.g.
code :
"%*d|%s|%*s|%s|%*d|%*s|%*d|%*s|%*s|%*f|%*f|%*s|%*s|%*f|%*f"
#include <stdio.h>
#include <string.h>

#define FLDW   32   /* max field width */
#define MAXC 1024   /* max chars in line */

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

    char buf[MAXC],     /* line buffer */
        name[FLDW],     /* storage for name */
        state[FLDW];    /* storage for state */

    /* use filename provided as 1st argument (stdin by default) */
    FILE *fp = argc > 1 ? fopen (argv[1], "r") : stdin;

    if (!fp) {  /* validate file open for reading */
        perror ("file open failed");
        return 1;
    }

    while (fgets (buf, MAXC, fp)) { /* read each line of input */
        /* parse 2nd & 4th fields as strings - you don't care about rest */
        if (sscanf (buf, "%*d|%31[^|]|%*[^|]|%31[^|]", name, state) == 2) {
            buf[strcspn (buf, "\n")] = 0;   /* trim \n from buf */
            /* output line with parsed name and state to right */
            printf ("%s  =>  name: %s, state: %s\n", buf, name, state);
        }
    }
    if (fp != stdin) fclose (fp);   /* close file if not stdin */

    return 0;
}
$ ./bin/fgetssscanf dat/field15pipes.txt
01|8a|0b|6c|82|1d|33|5e|4f|7.|0.|4g|3h|7.|5.  =>  name: 8a, state: 6c
01|9a|5b|0c|42|1d|93|3e|9f|8.|0.|5g|4h|6.|5.  =>  name: 9a, state: 0c
01|4a|5b|7c|22|0d|23|1e|1f|7.|2.|1g|5h|7.|7.  =>  name: 4a, state: 7c
01|8a|2b|5c|72|1d|53|6e|2f|1.|1.|8g|0h|7.|6.  =>  name: 8a, state: 5c
11|4a|6b|5c|92|2d|73|0e|6f|4.|2.|2g|7h|2.|4.  =>  name: 4a, state: 5c
01|2a|6b|0c|02|1d|83|0e|2f|5.|2.|9g|4h|3.|8.  =>  name: 2a, state: 0c
31|1a|0b|0c|72|2d|13|3e|3f|9.|0.|2g|5h|6.|9.  =>  name: 1a, state: 0c
01|8a|3b|7c|92|1d|93|3e|9f|6.|1.|4g|4h|8.|3.  =>  name: 8a, state: 7c
11|1a|4b|7c|42|2d|73|0e|5f|7.|0.|0g|5h|1.|7.  =>  name: 1a, state: 7c
21|8a|6b|9c|22|2d|23|2e|1f|9.|0.|1g|6h|6.|8.  =>  name: 8a, state: 9c
Please help correct this bug: reading integers line by line from a file using fscanf in c

Please help correct this bug: reading integers line by line from a file using fscanf in c


By : Ginger
Date : March 29 2020, 07:55 AM
hope this fix your issue You need to check if index is less than MAXARRAYSIZE or not. Otherwise, you will be going out of bounds and invoke undefined behavior (typically invalid memory access).
Change
fscanf a line from file in c

fscanf a line from file in c


By : lakshmi sindhura upp
Date : March 29 2020, 07:55 AM
like below fixes the issue That's because scanf's %s is specified as Matching a sequence of non-white-space characters. You want it to scanf for a sequence of non-semicolon characters. Left as an exercise :-) Hint: read the manual and see how the %[...] specifier works.
Also note that
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