Using variables within system command?

This is a discussion on Using variables within system command? within the C++ Programming forums, part of the General Programming Boards category; Hey guys, I'm not sure if what I'm trying to do is possible or the way I should do it. ...

  1. #1
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    Using variables within system command?

    Hey guys, I'm not sure if what I'm trying to do is possible or the way I should do it. Basically I want to ask for a hostname, a message and place them in string variables as host and msg respectively. The contents will then be parsed onto the "net send" system command.

    This is my best way of describing what I'm trying to do:
    Code:
    system("net send ") << host << msg << endl;
    If its not clear enough I can post more of the code.

  2. #2
    Sweet
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    Put that into one string and then pass it to the system command.

    Code:
    string systemSender = "net send ";
    
    systemSender += host + msg;
    
    system(systemSender.c_str());
    Woop?

  3. #3
    pwns nooblars
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    Though make sure to add spaces between the parameters.

  4. #4
    Sweet
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    How do you know it needs spaces . Maybe its comma sepeated
    Woop?

  5. #5
    pwns nooblars
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    Because generally if a person is using 2 different varaibles for a command such as that, it will need spaces between them because they are sperate parameters. Though I could be wrong, I doubt that I am.

  6. #6
    Sweet
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    It was a joke(just making sure you know that).
    Woop?

  7. #7
    pwns nooblars
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    I was just showing off my mind reading skills in my first post in this thread... then I had to back track so people didn't think I could read minds that way I don't get asked... "What am I thinking right now?!"

  8. #8
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    I got a compile error from Dev C++ telling me
    Code:
    systemSender += host + msg;
    is wrong, so I changed it to
    Code:
    systemSender += host, msg;
    and it compiles fine. Everything seems to be working fine except when I try "Host: 127.0.0.1" & "Msg: Hello" it tells me sending files are no longer supported. I think this is because the variables parsed mighten be spaced out after eachother, so its trying to perform this command:
    Code:
    net send 127.0.0.1Hello
    How can I space host and msg out?

  9. #9
    Sweet
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    Well, what are host and msg defined as? If the are just char * or char[] then yes that won't work.

    And to add a space you can make those strings and do this:
    Code:
    systemSender += host + " " + msg;
    Woop?

  10. #10
    pwns nooblars
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    Commas are not the same as most languages and lists when in programming languages. I am supprised that worked as it did.

    One thing you can do is
    Code:
    string systemSender = "net send " + host + " " + msg;

  11. #11
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    The +'s dont seem to work, I get an error on compile but I'll show you what does work.
    Code:
    #include <iostream>
    #include <dos.h>
    #include <string>
    
    using namespace std;
    
    char host[64], msg[512];
    string systemSender = "net send ";
    
    char getinfo()
    {
         cout<< "Hostname: ";
         cin.getline (host, 64, '\n');
         cout<< "Message: ";
         cin.getline (msg, 512, '\n');
    }
    
    char send()
    {
         systemSender += host;
         systemSender += " ";
         systemSender += msg;
         system(systemSender.c_str());
    }
    
    int main()
    {  
        getinfo();
        send();
        cin.get();
    }
    Anything I'm missing thats not letting me use "+ host + msg" ?

  12. #12
    Sweet
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    Yes like I said above the + operator isn't overloaded to take 2 char*'s which is what you are doing there.
    Woop?

  13. #13
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    So what can it take two of?

  14. #14
    Cat
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    Quote Originally Posted by moagim
    Anything I'm missing thats not letting me use "+ host + msg" ?
    Yes, you cannot concatenate character strings like that. The + operator only works if one or both arguments are std::string.
    You ever try a pink golf ball, Wally? Why, the wind shear on a pink ball alone can take the head clean off a 90 pound midget at 300 yards.

  15. #15
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    Sweet everything works thanks

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