Using winsock2, comparing two characters that seem to be equal comes out not equal

Question

Hello fine community at stackoverflow! I've been lurking around using the site for about a year now, and just have come to the need to post a question. I'm a bit of a klutz when it comes to coding, so go easy on me.

Here's the code (most of it is the sample winsock MSDN code :P):

Client:

#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>
#include <iostream>

// Need to link with Ws2_32.lib, Mswsock.lib, and Advapi32.lib
#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
#pragma comment (lib, "AdvApi32.lib")

void clarify(char *recvdata);
char mdata[7];

#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "10150"

int main(int argc, char **argv) 
{
    WSADATA wsaData;
    SOCKET ConnectSocket = INVALID_SOCKET;
    struct addrinfo *result = NULL,
                    *ptr = NULL,
                    hints;
    char recvbuf[DEFAULT_BUFLEN];
    int iResult;
    int recvbuflen = DEFAULT_BUFLEN;

    // Initialize Winsock
    iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
    if (iResult != 0) {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

    ZeroMemory( &hints, sizeof(hints) );
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    // Resolve the server address and port
    iResult = getaddrinfo("173.21.56.58", DEFAULT_PORT, &hints, &result);
    if ( iResult != 0 ) {
        printf("getaddrinfo failed with error: %d\n", iResult);
        WSACleanup();
        return 1;
    }

    // Attempt to connect to an address until one succeeds
    for(ptr=result; ptr != NULL ;ptr=ptr->ai_next) {

        // Create a SOCKET for connecting to server
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, 
            ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET) {
            printf("socket failed with error: %ld\n", WSAGetLastError());
            WSACleanup();
            return 1;
        }

        // Connect to server.
        iResult = connect( ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }

    freeaddrinfo(result);

    if (ConnectSocket == INVALID_SOCKET) {
        printf("Unable to connect to server!\n");
        WSACleanup();
        return 1;
    }

    // Send an initial buffer
    char sendbuf[512];
    std::cin.getline(sendbuf, 512);
    iResult = send( ConnectSocket, sendbuf, 512, 0 );
    if (iResult == SOCKET_ERROR) {
        printf("send failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }
    std::cout<<"sendbuf: "<<sendbuf<<"\n";
    std::cout<<"strlen(sendbuf): "<<strlen(sendbuf)<<"\n";

    printf("Bytes Sent: %ld\n", iResult);

    // Receive until the peer closes the connection
    do {

        iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
        if ( iResult > 0 )
            printf("Bytes received: %d\n", iResult);
        else if ( iResult == 0 )
            printf("Connection closed\n");
        else
            printf("recv failed with error: %d\n", WSAGetLastError());

        std::cout<<"recvbuf: "<<recvbuf<<"\n";
        std::cout<<"recvbuflen: "<<recvbuflen<<"\n";
        std::cout<<"strlen(recvbuf): "<<strlen(recvbuf)<<"\n";
        std::cout<<recvbuf[0]<<"\n";
        std::cout<<recvbuf[1]<<"\n";
        std::cout<<recvbuf[2]<<"\n";
        std::cout<<recvbuf[3]<<"\n";
        std::cout<<recvbuf[4]<<"\n";
        std::cout<<recvbuf[5]<<"\n";
        std::cout<<recvbuf[6]<<"\n";
        std::cout<<recvbuf[7]<<"\n";
        std::cout<<recvbuf[8]<<"\n";
        std::cout<<recvbuf[9]<<"\n";
        std::cout<<recvbuf[10]<<"\n";
        std::cout<<recvbuf[11]<<"\n";
        std::cout<<recvbuf[12]<<"\n";
        clarify(recvbuf);
        std::cout<<"mdata(main()): "<<mdata<<"\n";
        if (mdata == "anarchy") {std::cout<<"This is Anarchy. :)";}
        else {std::cout<<"Nope. :( ";}

    } while( iResult > 0 );

    std::cin.ignore();

    // shutdown the connection since no more data will be sent
    iResult = shutdown(ConnectSocket, SD_SEND);
    if (iResult == SOCKET_ERROR) {
        printf("shutdown failed with error: %d\n", WSAGetLastError());
        closesocket(ConnectSocket);
        WSACleanup();
        return 1;
    }
    // cleanup
    closesocket(ConnectSocket);
    WSACleanup();
    return 0;
}

void clarify(char *recvdata)
{
    std::cout<<"recvdata: "<<recvdata<<"\n";
    for (int i=0; i<(strlen(recvdata)); i++) {
        mdata[i]=recvdata[i];
        std::cout<<mdata[i]<<"\n";
    }
    std::cout<<"mdata(clarify()): "<<mdata<<"\n";
}

And the server code is the sample MSDN winsock code.

I realize the code has a bunch of sloppy extras added in, but rest assured, those are for my own thoughts and reminders. So, please don't bother telling me other places I could clean up. I'll take care of that when I get closer to finishing my project (a long way away :) ).

So, I'm having issues comparing the "mdata" variable with the characters "anarchy". Even when I send "anarchy" through winsock, it comes back as "anarchy", and I run it through "clarify()" just for good measure, it still doesn't seem to equal "anarchy".

I'm sure it's a noob mistake I'm making here, so please go easy on me...

EDIT: Here's the output after typing "anarchy" for the "sendbuf" input:

anarchy
sendbuf: anarchy
strlen(sendbuf): 7
bytes sent: 512
bytes recieved: 512
recvbuf: anarchy
recvbuflen: 512
strlen(recvbuf): 7
a
n
a
r
c
h
y

f
4
i
w
,
recvdata: anarchy
a
n
a
r
c
h
y
mdata(clarify()): anarchy
mdata(main()): anarchy
Nope :(

Answer 1

You're comparing the address of a c-string literal to the address stored in mdata.

if (mdata == "anarchy") {std::cout<<"This is Anarchy. :)";}

"anarchy" is a string literal, and has an address. You're comparing that arbitrary address with the address stored in the mdata variable. They're not the same addresses, so the equality check fails.

You don't mean to compare the addresses of where your two strings are stored, you mean to compare the characters stored at those strings.

strncmp is your friend here.