send（）函数返回更多需要c ++的字节 [英] send() function returns more bytes that it was required c++

问题描述

我正在做一个套接字程序，在我的服务器与设备连接后，我试图向他发送一条消息。但send（）函数返回的字节数大于存储在我的数组上的字节数。

以下是我的代码：

  StartSendingMessages（）
 {
 int retorno; 
 CString TextRetorno; 
 
 HEX_bufferMessage = new CHAR [7]; //有七个字节
 
 //指定状态
 HEX_bufferMessage [0] = 0xF0; 
 HEX_bufferMessage [1] = 0x15; 
 HEX_bufferMessage [2] = 0x31; 
 HEX_bufferMessage [3] = 0x04; 
 HEX_bufferMessage [4] = 0x02; // green 
 HEX_bufferMessage [5] = 0x0E; // C1 
 HEX_bufferMessage [6] = 0xF7; 
 
 retorno = send（sckSloMo，HEX_bufferMessage，sizeof（HEX_bufferMessage），0）; 
 
 TextRetorno.Format（％d，retorno）; // retorno = 8 
 AfxMessageBox（Bytes enviados：+ TextRetorno）; 
 
 if（retorno == SOCKET_ERROR）
 {
 AfxMessageBox（Error Send !!）; 
 return; 
} 
 else if（retorno！= 0）
 {
 AfxMessageBox（Send（）OK !!）; 
} 
} 
  

任何人都知道为什么会发生这种情况？

解决方案

您不是指 sizeof（HEX_bufferMessage）。 HEX_bufferMessage 的类型是[大概] char * ，大小为 char *

传送 7

<$>

p $ p> const int BUF_SIZE = 7;
char HEX_bufferMessage [BUF_SIZE];

// ...

retorno = send（sckSloMo，& HEX_bufferMessage [0]，BUF_SIZE，0）;


I am doing a socket program and, after my server is connected with the device, I am trying to send a message to him. But the send() function returns a number of bytes greater than the number of bytes that is stored on my array. And the message is not being sent.

Here is my code:

StartSendingMessages()
{
    int retorno;
    CString TextRetorno;

    HEX_bufferMessage = new CHAR[7]; // there are seven bytes

    // specifies the state
    HEX_bufferMessage[0] = 0xF0;
    HEX_bufferMessage[1] = 0x15;
    HEX_bufferMessage[2] = 0x31;
    HEX_bufferMessage[3] = 0x04;
    HEX_bufferMessage[4] = 0x02; // green
    HEX_bufferMessage[5] = 0x0E; // C1
    HEX_bufferMessage[6] = 0xF7;

    retorno = send(sckSloMo, HEX_bufferMessage, sizeof(HEX_bufferMessage), 0); 

    TextRetorno.Format("%d", retorno); // retorno = 8
    AfxMessageBox("Bytes enviados: " + TextRetorno);

    if (retorno == SOCKET_ERROR)
    {
        AfxMessageBox("Error Send!!");
        return;
    }
    else if(retorno != 0)
    {
        AfxMessageBox("Send() OK !!");
    }
}

Anyone knows why is this happening??

解决方案

You did not mean sizeof(HEX_bufferMessage). The type of HEX_bufferMessage is [presumably] char*, and the size of a char* is 8 bytes on your [64-bit] system.

Pass the number 7 instead, preferably using a constant, and get rid of that dynamic allocation if the value 7 really is fixed.

const int BUF_SIZE = 7;
char HEX_bufferMessage[BUF_SIZE];

// ...

retorno = send(sckSloMo, &HEX_bufferMessage[0], BUF_SIZE, 0); 

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