fscanf导致段错误

Question

I'm trying to read a bunch of int s from a .txt file and store them in memory. The fscanf() line in the below code is causing a segmentation fault whenever I try to run it, though. I've confirmed that `fopen() is working properly. Any idea what I should do? Thanks for your help.

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




void load_file(FILE* file, int** p);

int main()
{

    FILE* f1;
    f1 = fopen("twenty-five-ints.txt", "r");
    int p=0;
    int* k = &p;
    load_file(f1, &k);
    return 0;
}

void load_file(FILE* file, int** p) {

    int number = 0;
    int i = 0;
    while (fscanf(file, "%d", &number) != EOF) {
        *(*p + i) = (int) fscanf(file, "%d", &number);
        i++;
    }

}

Answer 1

In your code, p points to a pointer which points to a single integer. You only have enough space to store a single integer, attempting to store a second or third integer likely causes the crash you observe.

Answer 2

The problem is in

*(*p + i) = (int) fscanf(file, "%d", &number);

you have passed the address of a single int , and you're prerforming arithmatic opeation on the pointer to take it beyond the accessible memory. Accessing that memory invokes undefined behavior .

A segmentation fault is one of the side effects of UB.

That said, FWIW, there is no reason to cast the return value of fsacnf() to int .

Answer 3

Allocate p as an array of size 25 and initialize each element to zero.

That should solve the problem