Problems writing in array after malloc C

I'm having some problems trying to write in an array position of a struct, written by me, after assigned memory with the malloc function. I have to read some data from a file.txt (format for line: int string char. Those are an id for a person, a non particular string and a char that gives the "type" of the string to read and save), line per line, and save in the struct array. Unfortunately, often I have to add a data to a previous index in the struct array, but it seems that the program doesn't let me write in a previous index of the struct array. I don't know why. Hope I was clear enough. Thank you for your help!

Here's an example of file.txt:

    6         //number of lines
    3 tPar P
    2 tPar P
    3 tArr A
    1 tPar P
    1 tArr A
    2 tArr A

Here's the code:

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

#define DBG printf("Ok linea %d\n", __LINE__);


typedef enum { 
    false, 
    true 
} bool;

struct file {
    char name[15];
    int n;
    struct record *rec;
};

struct record {
    int cod;
    char tPar[10];
    char tArr[10];
};


int read(struct file *f) {

    FILE *fd;
    char str[100];
    int pCod;
    char pTime[10];
    char pChar;
    bool found;
    int i = 0;
    int j;

    fd = fopen(f->name, "r");

    if(!fd) {
        printf("Errore di apertura file.\n");
        exit(1);
    }

    fscanf(fd, "%d\n", &f->n);

    f->rec = malloc((f->n)*sizeof(struct record));

    if(f->rec == NULL) {
        printf("Errore nell'allocazione della memoria.\n");
        exit(1);
    }

    while(fgets(str, 100, fd)) {

        sscanf(str, "%d %s %c", &pCod, pTime, &pChar);
        pChar = toupper(pChar);
        found = false;

        f->rec[i].cod = 0;                  // these 4 lines are needed just
        strcpy(f->rec[i].tPar, "xxx");      // to check if it writes in the
        strcpy(f->rec[i].tArr, "xxx");      // struct array

        for(j=0; j<i; j++) {
            if((pCod == f->rec[j].cod) && (pChar == 'P')) {
                strcpy(f->rec[j].tPar, pTime);  // doesn't copy
                found = true;                   
            }
            if((pCod == f->rec[j].cod) && (pChar == 'A')) {
                strcpy(f->rec[j].tArr, pTime);  // doesn't copy
                found = true;                   
            }
        }

        if(!found) {
            f->rec[i].cod = pCod;
            if(pChar == 'P')
                strcpy(f->rec[i].tPar, pTime);
            if(pChar == 'A')
                strcpy(f->rec[i].tArr, pTime);

        }

        if(pChar == 'P')
            printf("%d %s %c\n", f->rec[i].cod, f->rec[i].tPar, pChar);
        if(pChar == 'A')
            printf("%d %s %c\n", f->rec[i].cod, f->rec[i].tArr, pChar);

        i++;

    }

    fclose(fd);

    return 0;

}


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

    struct file f;

    strcpy(f.name, argv[1]);

    read(&f);

    return 0;
}

Expected ouput:

3 tPar P
2 tPar P
3 tArr A
1 tPar P
1 tArr A
2 tArr A

Actual output:

3 tPar P
2 tPar P
0 xxx A
1 tPar P
0 xxx A
0 xxx A