malloc()总是可以增加数组的大小吗？

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

int main() {
    int *arr = NULL;
    int n = 0, new_size, i;

    printf("Enter the number of elements in the array: ");
    scanf("%d", &n);

    arr = (int *)malloc(n * sizeof(int));

    printf("Enter the elements of the array: ");
    for (i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    printf("Enter the new size of the array: ");
    scanf("%d", &new_size);

    arr = (int *)realloc(arr, new_size * sizeof(int));

    if (arr == NULL) {
        printf("Memory allocation failed.\n");
        return 1;
    }

    printf("The new array is: ");
    for (i = 0; i < new_size; i++) {
        printf("%d ", arr[i]);
    }

    free(arr);

    return 0;
}