c++ - 使用 cin 时的内存损坏 >>

Question

我在运行我的代码时遇到奇怪的内存损坏问题。它从以下 block 中的“cin”出现。有趣的是，for 循环第一次运行。内存损坏发生在第二次迭代(当 i = 1 时)。

case 3:
            {
                // for(int i = 0; i < MAX_PLAYERS; i++)
                for(int i = 0; i < 5; i++)
                {
                    mavlink_param_value_t packet_vel, packet_pwr;   
                    float vel_factor;
                    float power_factor;

                    strcpy(packet_vel.param_id, "GAME_VEL_FACTOR");
                    strcpy(packet_pwr.param_id, "GAME_PWR_FACTOR");

                    printf("Current index %d\n", i);
                    // cout << "\n" << "Enter Game Velocity Factor:";
                    // cin >> packet_vel.param_value;
                    cout << "\n" << "Enter Game Power Factor:";
                    cin >> power_factor;

                    printf("Assigning local variable to struct member\n");
                    packet_pwr.param_value = power_factor;

                    printf("Packing current message\n");
                    mavlink_msg_param_value_pack((uint8_t)i,
                                                 1,
                                                 &messages[i],
                                                 packet_vel.param_id, 
                                                 packet_vel.param_value, 
                                                 packet_vel.param_type,
                                                 1,
                                                 1);
                }

                *cont_mode = true;
                break;

错误如下:

Enter message for player 0
Current index 0

Enter Game Power Factor:1
Assigning local variable to struct member
Packing current message
Current index 1

Enter Game Power Factor:2
*** Error in `./send_mavlink_msgs': malloc(): memory corruption (fast): 0x0000000000ccf050 ***
Aborted (core dumped)

谢谢!

更新:

这是我创建“消息”的方式

    mavlink_message_t *messages = (mavlink_message_t *)malloc(num_of_robots*sizeof(mavlink_global_position_int_t));

找到它的定义here

Answer 1

mavlink_message_t *messages = (mavlink_message_t *)
   malloc(num_of_robots*sizeof(mavlink_global_position_int_t));

这大概应该是:

mavlink_message_t *messages = (mavlink_message_t *)
   malloc(num_of_robots*sizeof(mavlink_message_t));

使用错误的 sizeof 参数将分配错误的空间量。如果 mavlink_global_position_int_t 小于 mavlink_message_t(根据我粗略的谷歌搜索，似乎是这种情况)，这是一个严重的问题。

---

此外，我不熟悉“mavlink”是什么，但从 here 来看:

typedef struct __mavlink_param_value_t
{
 int8_t param_id[15]; ///< Onboard parameter id
 float param_value; ///< Onboard parameter value
 uint16_t param_count; ///< Total number of onboard parameters
 uint16_t param_index; ///< Index of this onboard parameter
} mavlink_param_value_t;

param_id 是一个 15 字节的数组。 "GAME_VEL_FACTOR" 和 "GAME_PWR_FACTOR" 如果算上末尾的 '\0' 终止符，它们都是 16 字节的字符串。