C在非常基本的C程序上编程EXC_BAD_ACCESS

Question

I am quite new to C programming. I need to write a programm that works with dynamic Arrays. (Takes in Values and doubles the size of the Array, when it is full). My programm is finished and compilation works but I keep on getting this Error in the commented line: Thread 1: EXC_BAD_ACCESS (code=2, address:(some long adress).

I have read on this and it seems that I may be pointing to null. But a null test didn't do the job. I'Ve had this problem in other programms before and I seem to be missing a basic point. Can somebody help me with this please! This is my code:

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

typedef struct{
    int *value;
    int size;
    int MAX;
} DynArray;

void dyn_array_add (DynArray* array){
    int wert;
    int *temp;
    printf("Geben Sie einen Wert ein:\n");
    scanf("%i", &wert);

    if (array->MAX==array->size) {
        for (int i= 0; i<array->MAX; i++) {
            temp[i] = array->value[i];  // error occurs HERE
        }
        free(array->value);

        array->MAX = array->MAX*2;
        array->value=malloc(sizeof(int)* array->MAX);
        for (int i= 0; i<array->MAX; i++) {
            array->value[i] = temp[i];
        }
    }

    array->value[array->size]= wert;
    array->size++;
    for (int i = 0; i < array->MAX; i++) {
        printf("Value[%i]: %i \n", i, array->value[i]);
    }
}

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


    DynArray* array;
    array = (DynArray*)malloc(sizeof(DynArray));
    array->MAX=5;
    array->size=0;
    array->value=malloc(sizeof(int)* array->MAX);

    while (1) {
        dyn_array_add(array);

    }
    return 0;
}

Answer 1

temp[i] = array->value[i];  // error occurs HERE

显然，因为你没有为temp分配内存。