Is there any encoding problems?

Question

I am trying to write these parameters in a file .txt, but when I open the file (even before that it shows me a warining about the encoding) it appers like a bug, full of ????, like this:

$�U�z�G��?xpto%�U\���(\�?xpto&�Uףp=
��?xpto'�UR���Q�?xpto(�U�������?xpto)�UH�z�G�?xpto*�U��(\���?xpto+�U>
ףp=�?xpto,�U���Q��?xpto-�U433333�?xpto

I've searched a lot about but as it is a specifically error, i cannot find nothing about it. What is happening?

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

typedef struct
{
    int age;
    double height;
    char name[64];
} Person;

void printPersonInfo(Person *p)
{
    printf("Person: %s, %d, %f\n", p->name, p->age, p->height);
}

int main (int argc, char *argv[])
{
    FILE *fp = NULL;
    int i;
    Person p = {35, 1.65, "xpto"};

    /* Validate number of arguments */
    if(argc != 2)
    {
        printf("USAGE: %s fileName\n", argv[0]);
        return EXIT_FAILURE;
    }

    /* Open the file provided as argument */
    errno = 0;
    fp = fopen(argv[1], "w");
    if(fp == NULL)
    {
        perror ("Error opening file!");
        return EXIT_FAILURE;
    }

    /* Write 10 itens on a file */
    for(i = 0 ; i < 10 ; i++)
    {    
        p.age = p.age+1;
        p.height = p.height+0.03;
        fwrite(&p, sizeof(Person), 1, fp);
    }

    fclose(fp);

    return EXIT_SUCCESS;
}

Answer 1

The fwrite function is writing the binary representation of the struct p to the file. If you want to write text, use fprintf:

fprintf(fp, "%d %f %s\n", p.age, p.height, p.name);