fscanf() function puts a \000 at the first char read

Question

Im trying to read a file with this format:

05874121 A 7
07894544 C 3
05655454 B 5
05879544 B 6
05763465 C 2

and assign each 'word' to different variables (dni, model, trash)

This code is running on Linux, and I use CLion for debugging.

char *path = "file.txt";
FILE *f;
int result;
char dni[9], model[1], trash[100];

f = fopen(path, "r");
do {
    result = fscanf(f, "%s %s %s", dni, model, trash);
    printf("DNI: %s\n", dni);
}
while( result > 0);

fclose(f);

This should print the first column values, but when I execute the program, the output is just: "DNI: " "DNI: " "DNI: " ... and so on.

While debugging, I realized that "dni" store correctly all the numbers (as chars), but the very first element, dni[0], is always: 0 '/000' like if it was the end of the string.

I dont know why is happening this.

Answer 1

I did 2 corrections in your code:

#include <stdio.h>
int main (int argc, char ** argv) {
        char *path = "file.txt";
        FILE *f;
        int result;
        char dni[9], model[2], trash[100];

        f = fopen(path, "r");
        while(1) {
            result = fscanf(f, "%s %s %s", dni, model, trash);
            if (result < 1) break;
            printf("DNI: %s model %s trash %s\n", dni, model, trash);
        }

        fclose(f);
        return 0;
}

First, the variable model[2] must have an extra character for the end of the string.

Then, the line "if (result <1) break;".

Probably, the error was the model[1] with only one character. The \\ 000 in dni can be the end of the model string.