C ++字符串数组在20字节后拆分

Question

我有这个代码示例，用于制作最终将通过BLE发送的20字节大小的数据包。 我想更改代码，以便输入我的数据数组（加速度计读数）。

我的数据：

float ax, ay, az, gx, gy, gz, mx, my, mz, yaw, pitch, roll;
char myConcatenation[80];
sprintf(myConcatenation, "%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f", ax,  ay, az, gx, gy, gz, mx, my, mz, yaw, pitch, roll);

功能定义：

std::vector<std::string> buildPackets(std::string data, size_t packetSize) {
  // split up the packet
  size_t partialPacketSize = packetSize - 4;

  // calculate how many packets
  size_t packetCount = data.length() / partialPacketSize;
  packetCount = data.length() % partialPacketSize == 0 ? packetCount : packetCount + 1;

  std::vector<std::string> packets;
  // construct each packet
  for (int i = 0; i < packetCount; i++) {
    // start of packet
    std::string packet = "##";
    packet += (char)packetCount;
    packet += (char)(i + 1);
    std::string part = i == packetCount - 1 ? data.substr(i * partialPacketSize) : data.substr(i * partialPacketSize, partialPacketSize);
    packet.append(part);

    // add to vector of packets
    packets.push_back(packet);
  }

函数调用：这里的变量data是字符串，我需要的就是放在myConcatenation[]

我应该在代码中进行哪些更改才能使其正常工作？

   std::string data = "averylongstringofdatathatislargerthantwentycharacters";
size_t chars = data.length();
size_t packetSize = 20;

// assume I have this characteristic already setup
if (chars > packetSize) {
  auto packets = buildPackets(data, packetSize);
  for (auto packet : packets) {
    txCharacteristic->setValue(packet);
    txCharacteristic->notify();
  }
}
else {
  txCharacteristic->setValue(data);
  txCharacteristic->notify();
}

感谢您的任何帮助。

---

编辑：

this is what I have now: 

std::vector<std::string> buildPackets(std::string data, size_t packetSize) {
  // split up the packet
  size_t partialPacketSize = packetSize - 4;

  // calculate how many packets
  size_t packetCount = data.length() / partialPacketSize;
  packetCount = data.length() % partialPacketSize == 0 ? packetCount : packetCount + 1;

  std::vector<std::string> packets;
  // construct each packet
  for (int i = 0; i < packetCount; i++) {
    // start of packet
    std::string packet = "@";
    packet += (char)packetCount;
    packet += (char)(i + 1);
    std::string part = i == packetCount - 1 ? data.substr(i * partialPacketSize) : data.substr(i * partialPacketSize, partialPacketSize);
    packet.append(part);

    // add to vector of packets
    packets.push_back(packet);
  }

  return packets;
}


--------
**call function**

sprintf(myConcatenation, "#%3.2f,%3.2f,%3.2f,#%3.2f,%3.2f,%3.2f,#%3.2f,%3.2f,%3.2f,#%3.2f,%3.2f,%3.2f", ax,  ay, az, gx, gy, gz, mx, my, mz, yaw, pitch, roll);

size_t packetSize = 20;

auto packets = buildPackets(myConcatenation, packetSize);
  for (auto packet : packets) {
    pCharacteristic->setValue(packet);
    pCharacteristic->notify();
  }

  Serial.println(myConcatenation);

---

我可以问你接收方吗？ 我的字符串在每个不同传感器读数的开头都有# （＃ax，ay，az，＃gx，gy ...）和@在每个数据包的开头。 你知道应该如何实现接收方（我在MITAppInventor中这样做但我想不出如何按顺序连接数据包并将它们附加到.csv文件中。（每列=不同的数据）。

谢谢！

Answer 1

String类提供了一个构造函数，它接受输入const char *，因此您可以使用它将您的变量命名数据（隐式或显式）转换为std :: string。

所以最后，只需将其传递给函数即可

float ax, ay, az, gx, gy, gz, mx, my, mz, yaw, pitch, roll; char myConcatenation[80]; sprintf(myConcatenation, "%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f,%3.2f", ax, ay, az, gx, gy, gz, mx, my, mz, yaw, pitch, roll); auto packets = buildPackets(myConcatenation, packetSize);

就这样。

一个快速的额外建议：

• 用sprintf_s改变sprintf，它更安全

字符串引用