首次看到的C语言语句，希望能解释一下

Question

看不懂的C语言语句，希望能给解释一下。
是指针变量作为数组的名字？

#include <stdio.h>
#include <Windows.h>

void main(void)
{
    unsigned char i;
    unsigned char * j;
    j[2]=3;
    
    printf("hello world!\r\n");
    system("pause");
    
}

参考的代码

```c
static ret_code_t ble_device_addr_encode(uint8_t  * p_encoded_data,
                                         uint16_t * p_offset,
                                         uint16_t   max_size)
{
    ret_code_t     err_code;
    ble_gap_addr_t device_addr;

    // Check for buffer overflow.
    if (((*p_offset) + AD_TYPE_BLE_DEVICE_ADDR_SIZE) > max_size)
    {
        return NRF_ERROR_DATA_SIZE;
    }

    // Get BLE address.
    err_code = sd_ble_gap_addr_get(&device_addr);
    VERIFY_SUCCESS(err_code);

    // Encode LE Bluetooth Device Address.
    p_encoded_data[*p_offset]  = (uint8_t)(AD_TYPE_FIELD_SIZE +
                                               AD_TYPE_BLE_DEVICE_ADDR_DATA_SIZE);
    *p_offset                 += AD_LENGTH_FIELD_SIZE;
    p_encoded_data[*p_offset]  = BLE_GAP_AD_TYPE_LE_BLUETOOTH_DEVICE_ADDRESS;
    *p_offset                 += AD_TYPE_FIELD_SIZE;
    memcpy(&p_encoded_data[*p_offset], &device_addr.addr[0], BLE_GAP_ADDR_LEN);
    *p_offset                 += BLE_GAP_ADDR_LEN;
    if (BLE_GAP_ADDR_TYPE_PUBLIC == device_addr.addr_type)
    {
        p_encoded_data[*p_offset] = AD_TYPE_BLE_DEVICE_ADDR_TYPE_PUBLIC;
    }
    else
    {
        p_encoded_data[*p_offset] = AD_TYPE_BLE_DEVICE_ADDR_TYPE_RANDOM;
    }
    *p_offset += AD_TYPE_BLE_DEVICE_ADDR_TYPE_SIZE;

    return NRF_SUCCESS;
}

```

Answer 1

严格来说
unsigned char * j;
j[2]=3;
这是错误的，因为j没有初始化
但是结果是什么，就是未知了
应该写
unsigned char * j = (unsigned char *)malloc(sizeof(unsigned char) * 10);
j[2]=3;