将struct转换为byte并返回struct

I'm currently working with Arduino Unos, 9DOFs, and XBees, and I was trying to create a struct that could be sent over serial, byte by byte, and then re-constructed into a struct.

我目前正在使用Arduino Unos,9DOF和XBees,我正在尝试创建一个结构,可以通过串行,逐字节发送,然后重新构造成结构。

So far I have the following code:

到目前为止,我有以下代码:

struct AMG_ANGLES {
    float yaw;
    float pitch;
    float roll;
};

int main() {
    AMG_ANGLES struct_data;

    struct_data.yaw = 87.96;
    struct_data.pitch = -114.58;
    struct_data.roll = 100.50;

    char* data = new char[sizeof(struct_data)];

    for(unsigned int i = 0; i<sizeof(struct_data); i++){
        // cout << (char*)(&struct_data+i) << endl;
        data[i] = (char*)(&struct_data+i); //Store the bytes of the struct to an array.
    }

    AMG_ANGLES* tmp = (AMG_ANGLES*)data; //Re-make the struct
    cout << tmp.yaw; //Display the yaw to see if it's correct.
}

Source: http://codepad.org/xMgxGY9Q

This code doesn't seem to work, and I'm not sure what I'm doing wrong.

这段代码似乎不起作用,我不确定我做错了什么。

How do I solve this?

我该如何解决这个问题?

4 个解决方案

#1

It seems I've solved my issue with the following code.

看来我用以下代码解决了我的问题。

struct AMG_ANGLES {
    float yaw;
    float pitch;
    float roll;
};

int main() {
    AMG_ANGLES struct_data;

    struct_data.yaw = 87.96;
    struct_data.pitch = -114.58;
    struct_data.roll = 100.50;

    //Sending Side
    char b[sizeof(struct_data)];
    memcpy(b, &struct_data, sizeof(struct_data));

    //Receiving Side
    AMG_ANGLES tmp; //Re-make the struct
    memcpy(&tmp, b, sizeof(tmp));
    cout << tmp.yaw; //Display the yaw to see if it's correct
}

WARNING: This code will only work if sending and receiving are using the same endian architecture.

警告:此代码仅在发送和接收使用相同的endian体系结构时才有效。

#2

You do things in the wrong order, the expression

你以错误的顺序做事,表达式

&struct_data+i

takes the address of struct_data and increases it by i times the size of the structure.

获取struct_data的地址并将其增加i倍于结构的大小。

Try this instead:

试试这个:

*((char *) &struct_data + i)

This converts the address of struct_data to a char * and then adds the index, and then uses the dereference operator (unary *) to get the "char" at that address.

这会将struct_data的地址转换为char *,然后添加索引,然后使用解除引用运算符(一元*)来获取该地址的“char”。

#3

Always utilize data structures to its fullest..

始终充分利用数据结构..

union AMG_ANGLES {
  struct {
    float yaw;
    float pitch;
    float roll;
  }data;
  char  size8[3*8];
  int   size32[3*4];
  float size64[3*1];
};

#4

for(unsigned int i = 0; i<sizeof(struct_data); i++){
    // +i has to be outside of the parentheses in order to increment the address
    // by the size of a char. Otherwise you would increment by the size of
    // struct_data. You also have to dereference the whole thing, or you will
    // assign an address to data[i]
    data[i] = *((char*)(&struct_data) + i); 
}

AMG_ANGLES* tmp = (AMG_ANGLES*)data; //Re-Make the struct
//tmp is a pointer so you have to use -> which is shorthand for (*tmp).yaw
cout << tmp->yaw; 
}

#1