setsockopt在KEEP_ALIVE期间发出错误 [英] setsockopt gives an error during the KEEP_ALIVE

问题描述

#include "stdafx.h"
#include <stdio.h>
#include <windows.h>

int _tmain(int argc, _TCHAR* argv[])
{
    WSADATA wsaData = {0};
    int nResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    SOCKET sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    BOOL bOptVal = TRUE;
    setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE , &bOptVal, sizeof(bOptVal));
    return 0;
}

它给出了一个错误



错误C2664：''setsockopt''：无法将参数4从''BOOL *''转换为''const char *''

Its gives an error

error C2664: ''setsockopt'' : cannot convert parameter 4 from ''BOOL *'' to ''const char *''

推荐答案

setsockopt 采用C样式字符串 const char * 不是 bool 作为第4个参数。



你可以尝试：

setsockopt takes a C style string const char* not a bool as its 4th parameter.

You could try:

const char* Optval = "true";
setsockopt( sock, SOL_SOCKET, SO_KEEPALIVE, Optval, strlen( Optval ) );

这可能会编译但是会工作？这取决于与 SO_KEEPALIVE 相关联的潜在参数值。根据这个 [ ^ ] C样式字符串实际上是一个伪装的整数，所以代码应该是

That will likely compile but will it work? That depends on the potential parameter values associated with SO_KEEPALIVE. According to this[^] the C style string is really a disguised integer so the code should be

int iOptval = 1;
int iOptSize = sizeof( int );
setsockopt( sock, SOL_SOCKET, SO_KEEPALIVE, reinterpret_cast< char* >( &iOptval ), iOptSize );

查看 setsockopt（）函数 [ ^ ] in MSDN和示例。第4个参数是指向存储结果的缓冲区的指针。指针的类型是 const char * ，以允许不同的值类型。其他实现（POSIX）使用 const void * 更清楚地表明这一点。



使用BOOL值，只需施放指针：

See the setsockopt() function[^] in the MSDN and the examples. The 4th parameter is a pointer to a buffer where the result is stored. The type of the pointer is const char * to allow different value types. Other implementations (POSIX) use const void * which indicate this more clearly.

With a BOOL value, just cast the pointer:

BOOL bOptVal = TRUE;
setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE ,(const char *)&bOptVal, sizeof(bOptVal));

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