FILE *f;
char line[LINE_SIZE];
char *lines;
int num_righe;

f = fopen("spese.dat", "r");

if(f == NULL) {
	f = fopen("spese.dat", "w");
}

while(fgets(line, LINE_SIZE, f)) {
	num_righe++;
	lines = realloc(lines, (sizeof(char)*LINE_SIZE)*num_righe);
	strcpy(lines[num_righe-1], line);
}

fclose(f);

spese.c:29: warning: assignment makes integer from pointer without a cast
spese.c:30: warning: incompatible implicit declaration of built-in function ‘strcpy’
spese.c:30: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast

FILE *f;
char line[LINE_SIZE];
char **lines = NULL;
int num_righe = 0;

f = fopen("spese.dat", "r");

if(f == NULL) {
        f = fopen("spese.dat", "w");
}

while(fgets(line, LINE_SIZE, f)) {
        num_righe++;
        lines = (char**)realloc(lines, sizeof(char*)*num_righe);
        lines[num_righe-1] = strdup(line);
}

fclose(f);

char * strcpy ( char * destination, const char * source );

strcpy(lines[num_righe-1], line);

strcpy(lines + (num_righe-1), line);

lines = realloc(lines, (sizeof(char)*LINE_SIZE)*num_righe);

if (!lines) //MUST HANDLE NULL POINTER!!

/* string copy code here*/

fscanf(f, "%sn", line[index]);
index++;