c++ using namespace std 导致 bind () 错误和迭代器放弃

Question

I have the problem when I add

using namespace std;

that the compiler says that there is no confection to long for bind.

simple example:

#include <winsock2.h>
#include <mutex>
#include <iostream>

using namespace std;

int main()
{
    WSADATA wsa;
    long rc = WSAStartup(MAKEWORD(2, 0), &wsa);
    SOCKADDR_IN addr;
    SOCKET acceptSocket = socket(AF_INET, SOCK_STREAM, 0);


    memset(&addr, 0, sizeof(SOCKADDR_IN));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(1234);
    addr.sin_addr.s_addr = ADDR_ANY;
    rc = bind(acceptSocket, (SOCKADDR*)&addr, sizeof(SOCKADDR_IN));

    return 0;
}

it would be a simple one now

using namespace std;

to renounce... but I have further:

    std::vector<Structs*>::iterator it = m_ClientList.begin();
    for (; it != m_ClientList.end(); ++it)

and when i remove the using namespace std I get the following error message:

C2672 "std :: invoke": no matching overloaded function found 
C2893 Function template "unknown-type std :: invoke (_Callable &&, _ Types && ...) noexcept (<expr>)" could not be specialized 

I don't know where to put another std:: in

std::vector<Structs*>::iterator it = m_ClientList.begin();

not before iterator...

Answer 1

Don't use using namespace std; . You've run into the main problem it causes:

• There exists a function in the std namespace called bind .
• There exists a function in the WinSock2 Sockets library called bind .

By including using namespace std , the compiler does not know which one to pick.

Regardless, using using namespace std or not, forces you to disambiguate the calls via std::bind(...) and ::bind(...)

The error you are getting with std::invoke is a separate issue. Are you including the <functional> header?

---

As for this:

std::vector<Structs*>::iterator it = m_ClientList.begin();
for (; it != m_ClientList.end(); ++it)

Use auto and a range-based-for-loop :

for(auto& client : m_ClientList) {
    //...
}