将 64 位 int 值写入 NSOutputStream

发布于 2024-09-08 23:25:51 字数 379 浏览 4 评论 0原文

我在将位置坐标传送到网络上连接的一组电机时遇到问题。我可以很好地发送一个字符串，并从电机接收回文本，但我似乎无法向它发送一个 int 值。

使用 NSlog 我已经确定我发送的实际值是正确的，但是我怀疑我通过输出流发送它的方法是错误的。有什么想法吗？

我发送 64 位 int 值的代码：

uint64_t rawInt = m1; 
rawInt <<= 16; 
rawInt |= m2;
NSData *buffer = [NSData dataWithBytes: &rawInt length:8];
[outputStream write: [buffer bytes] maxLength:[buffer length]];

原文

I'm having trouble communicating position coordinates to a set of motors I have connected on the network. I can send a string just fine, and receive text back from the motor, but I can't seem to send it an int value.

Using NSlog I have determined that the actual value I'm sending is correct, however I suspect my method of sending it via the output stream is wrong. Any ideas?

My code for sending a 64bit int value:

uint64_t rawInt = m1; 
rawInt <<= 16; 
rawInt |= m2;
NSData *buffer = [NSData dataWithBytes: &rawInt length:8];
[outputStream write: [buffer bytes] maxLength:[buffer length]];

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猫弦 2024-09-15 23:25:51

嗯，你的代码看起来有点有趣。无论如何，为了通过网络发送二进制整数，您必须知道字节序：接收器期望小字节序或大字节序整数。

这是两者的代码：

uint64_t myInt = 42;

uint64_t netInt = CFSwapInt64HostToLittle(myInt); // use this for little endian
uint64_t netInt = CFSwapInt64HostToBig(myInt);    // use this for big endian

[outputStream write:(uint8_t*)&netInt maxLength:sizeof(netInt)];

Well, your codes looks kind of funny. Anyway, for sending a binary integer over the network, you have to know the endianess: The receiver either expects little or big endian integers.

Here's the code for both:

uint64_t myInt = 42;

uint64_t netInt = CFSwapInt64HostToLittle(myInt); // use this for little endian
uint64_t netInt = CFSwapInt64HostToBig(myInt);    // use this for big endian

[outputStream write:(uint8_t*)&netInt maxLength:sizeof(netInt)];

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