C + Malloc中的结构

Question

I have this [UPDATED]

typedef struct Cerchi { 
    char nome[4];
    int x; //coordinate centro
    int y; //coordinate centro
    int r; //raggio
}cerchio;

   cerchio *leggi_file ( FILE *fp)
{
            char buffer[100]; 
            int i=0;    
            cerchio *bufcer;
            bufcer=(cerchio *)malloc(sizeof (int)*10000000);               
                while(fgets(buffer, sizeof(buffer), fp)!= NULL) //Fino a che file non è null
                         {  
                         //bufcer=realloc(bufcer, sizeof(int)*100);
                         sscanf(buffer, "%s %d %d %d",bufcer[i].nome,&bufcer[i].x,&bufcer[i].y,&bufcer[i].r);
        /*stampa di controllo*/          printf("\n%s %d %d %d",bufcer[i].nome,bufcer[i].x,bufcer[i].y,bufcer[i].r); 
                         i++;                
                         }
                         return bufcer;


}

This function is working. That's the UPDATED main

int main(int argc, char *argv[]) {
    FILE *fp;
if (argc < 2) {
    printf("Mancano parametri da tastiera\n"); //Sempre >=1 parametri passati
    exit(1);
}
fp = fopen(argv[1], "r");
if (fp == NULL) {
    printf("Impossibile aprire il file\n");
    exit(1);
}
    struct Cerchi *bufcer = NULL;
bufcer = leggi_file(fp);
stampa(bufcer); 
//vettore = leggi_file(FILE *fp);    E R R O R E
fclose(fp);

return 0;
}

I'm not able to print my *bufcer struct in this function

    void stampa(bufcer)
{
int i;
for (i=0;i<50;i++)
 {
 printf("\n%s %d %d %d",bufcer[i]->nome,bufcer[i]->x,bufcer[i]->y,bufcer[i]->r); 
 }
}

Please try to help me , tomorrow morning i have an exam about it [UPDATED] Wich error i'm doing? Can you try to solve it and help me? Thanks a lot....

Answer 1

You have to use -> operator when accessing structure elements, so your printf will be as

printf("\\n%s %d %d %d",bufcer[i]->nome,bufcer[i]->x,bufcer[i]->y,bufcer[i]->r);

Also, -> operator use for scanf()

You need to pass & of structure to pass structure pointer

Answer 2

1. Do not cast return value of malloc() .
2. Always check the return value of sscanf() to ensure all the elements got scanned successfully.
3. Change stampa( struct Cerchi *bufcer); to stampa(bufcer); This is a function call not a function definition or declaration. Also, add struct Cerchi *bufcer = NULL; inside main() before calling stampa() .

4. You are not using the return value of leggi_file () . As per your logic, you need to collect the value in bufcer . Change your code to

   bufcer = leggi_file(fp);

5. Always check for the success of malloc() before using the returned pointer.