我还是c ++的新手。我想阅读几个来源的消息。每个源将以4个字符ID开始数据消息。每个人也会有几条数据信息。没有任何消息具有我想从设备获得的所有信息。因此，如果我创建一个以ID作为对象名称的对象，下次收到消息时，对象是否会更新或完全重建？有没有办法在代码中调用之前检查对象是否已构造？
class Channels{
public:
INT8U systemID; //0x01 Glonass, 0x02 GPS
INT8U satID;
INT8U GlonassNumber;
INT8U SNR; //signal to noise ratio
FP64 carrierPhase; //cylces
FP64 psuedoRange; //milliseconds
FP64 doppler; //HZ cycles
float tropDelay; //meters
float ionoDelay; //meters
};
class BaseStation{
public:
Channels channel[32]; //each channel object has all channel class variables in it
int numberSatelitesTracked;
FP64 timeUTC;
INT16U week;
FP64 GPStoUTCoffset;
FP64 GLOtoUTCoffset;
INT8S recieverTimeOffset;
FP64 posX; //geocentric coordinates in meters
FP64 posY;
FP64 posZ;
FP64 rmsX; //expected root mean square error of coordinates
FP64 rmsY;
FP64 rmsZ;
};
if( check == SOCKET_ERROR){
if( WSAGetLastError() != WSAEWOULDBLOCK){
printf("base station client recieve failed with error %d \n", WSAGetLastError());
FreeSocketInformation(i); //shuts down client socket if no data
}
continue;
}
else{
//recieve bytes into array
memcpy(recvArray, SocketInfo->DataBuf.buf, SocketInfo->RecvBytes +1);
//print recieved bytes on screen
printf("%s \n", SocketInfo->DataBuf.buf);
//first 4 bytes in message are base ID
cBuffer[0] = recvArray[0];
cBuffer[1] = recvArray[1];
cBuffer[2] = recvArray[2];
cBuffer[3] = recvArray[3];
baseID = cBuffer;
//create object with 4 char name
BaseStation baseID;
//test message identity and sort data
if(recvArray[4] == 0x10 && recvArray[5] == 0xF5){
baseID.timeUTC = combine64(recvArray[6]);
baseID.week = combine16u(recvArray[14]);
baseID.GPStoUTCoffset = combine64(recvArray[16]);
baseID.GLOtoUTCoffset = combine64(recvArray[24]);
baseID.recieverTimeOffset = recvArray[32];
int noChannels = (check-30) /30 ;
if (noChannels >= 32){
noChannels = 32;
}
int x = 33;
for(int m = 0; m < noChannels; m++){ //advance reading for channel m
baseID.channel[m].systemID = recvArray[x];
x++;
baseID.channel[m].satID = recvArray[x];
x++;
baseID.channel[m].GlonassNumber = recvArray[x];
x++;
baseID.channel[m].SNR = recvArray[x];
x++;
baseID.channel[m].carrierPhase = combine64(recvArray[x]);
x = x+8;
baseID.channel[m].psuedoRange = combine64(recvArray[x]);
x = x+8;
baseID.channel[m].doppler = combine64(recvArray[x]);
x = x+10;
} //end of for loop to gather F5 sat data
} //end F5 message data
if(recvArray[4] == 0x10 && recvArray[5] == 0xF6){
baseID.posX = combine64(recvArray[6]);
baseID.posY = combine64(recvArray[14]);
baseID.posZ = combine64(recvArray[22]);
baseID.rmsX = combine64(recvArray[30]);
baseID.rmsY = combine64(recvArray[38]);
baseID.rmsZ = combine64(recvArray[46]);
} //end F6 message data
好吧所以看起来阵列对我来说可能是最好的。因此，如果我设置100个基础对象，然后使用第二个布尔数组跟踪活动数组元素，这看起来应该有效吗？ （baseID添加到基础对象）
BaseStation base[100];
boolean baseActive[100];
int baseNumber;
//begin message processing------------------------------------------------------------
//first 4 bytes in message are base ID
cBuffer[0] = recvArray[0];
cBuffer[1] = recvArray[1];
cBuffer[2] = recvArray[2];
cBuffer[3] = recvArray[3];
string name = cBuffer;
//check for existing baseID------------------------------------------------------------
// 100 array positions
//find if base is already in use, create new if not in use
for(baseNumber = 0; base[baseNumber].baseID != name; baseNumber++){
//for statement increases untill it finds baseID == name
if( baseNumber >= 100){ //baseID not currently in use
for(int n=0; baseActive[n] == true; n++){
//for statement increases untill finds a false baseActive
baseNumber = n; //assign baseNumber to the array position
base[baseNumber].baseID = name; //create new baseID
continue;
}
}
}
//check and process message data--------------------------------------------------------
if( base[baseNumber].baseID == name){
baseActive[baseNumber] = true;
//test message identity and sort data
}//end of for loop
//test connection, if no bytes recieved then connection is closed.----------------------
if( SocketInfo->RecvBytes == 0){
FreeSocketInformation(i); //shuts down client socket if no data
continue;
}
}
} //end of read data from socket
}
//need to add a timer to remove non sending bases from the baseActive[] array
答案 0 :(得分：3)
C ++是一种静态类型语言，您需要在编译时提供对象名称 您无法在运行时创建对象名称并使用该名称创建对象。
答案 1 :(得分：1)
正如已经回答的那样，你不能在C ++中这样做。 但是，您可以通过其他方式解决您的问题。 首先，您需要将一些ID绑定到结构BaseStation的某个具体对象。您可以通过两种方式提供此链接 - 将BaseStation对象保存在关联容器中，其中键是ID，或者通过保存BaseStation对象数组（据我所知，您正在编写某种类型的微控制器代码，因此std容器可能不是可供你使用）。
第一个方法代码示例：
//id is 4 char so it can be thought as int on most systems
std::map<int, BaseStation *> baseStations;
int * id = (int*)recvArray; //this hack is for showing how you can convert 4 char to int
//may be in your code (int id = combine32(recvArray[0])) is equvivalent
if(baseStations.find(*id) != baseStations.end()) //checking existance of object with such id
{
//ok, exists, do nothing
}
else
baseStations[*id] = new BaseStation(); //create new
baseStations[*id].timeUTC = combine64(recvArray[6]); //starting copying values
//other values copying
在第二种情况下，如果由于微控制器内存不足而无法使用关联容器或无法负担其libs \代码，则可以仅使用数组，但它根本不灵活并且消耗更多操作。例如：
//BaseConnection also holds field names id;
BaseConnection baseConnections[N];
int FindId(int id); //return index of element in baseConnections array with this id
BaseConnection * workingConnection = &baseConnections[FindId(combine32(recvArray[0]))];
workingConnection->timeUTC = combine64(recvArray[6]); //starting copying values
//other values copying