The last result of CMD command can not be caught?

See more:

C++

cmd

I am trying to execute a command in the command line prompt. This command is sent from c++. If i am trying to execute 3 command, only 2 is executed and the third is not returned to c++.
Here is what i am trying to execute:

wmic diskdrive get serialnumber& wmic cpu get ProcessorId& wmic os get SerialNumber& echo %username%

Here is the code snippet of catching the return from CMD my prog:

cmd.append("2>&1");

    std::string data;
    FILE * stream;
    const int char_length= 256;
    char buffer[char_length];

    stream = popen(cmd.c_str(), "r");
    if (stream)
    {
        while (!feof(stream))
        if (fgets(buffer, char_length, stream) != NULL)
            data.append(buffer);
        pclose(stream);
     }
    return data;

The returned code contain information about the first 3 command. I thought that there is some issue about the last command but when trying to swap the command the last command was not also caught by the programme.

What I have tried:

I have walked around the problem by making the last command a useless one (that i do not need), i made it:

C++

echo

std::string cmd("wmic diskdrive get serialnumber& wmic cpu get ProcessorId& echo %username%& wmic os get SerialNumber& echo");

i think there must be a solution for this, thanks in advance for help