what is the C++ version of this C code ?

This is a discussion on what is the C++ version of this C code ? within the C++ Programming forums, part of the General Programming Boards category; hi, i want to extract data from a line. something like.... char buff[100]; in.getline(buff,100); // in is an inputstream object ...

  1. #1
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    Exclamation what is the C++ version of this C code ?

    hi, i want to extract data from a line.

    something like....

    char buff[100];
    in.getline(buff,100); // in is an inputstream object
    if(sscanf(buff,"%d %d",&var1,&var2)==2) // what is the C++
    //version of this line ?
    cout<<var1<<" "<<var2<<endl;


    there are several ways to read data...but i want to know, what is the equivalent code for sscanf() in C++ ? is it possible at all ?
    blue_gene

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    C++ Witch laserlight's Avatar
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    you can use sscanf() in C++, but you'll need to #include <cstdio>
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
    I get maybe two dozen requests for help with some sort of programming or design problem every day. Most have more sense than to send me hundreds of lines of code. If they do, I ask them to find the smallest example that exhibits the problem and send me that. Mostly, they then find the error themselves. "Finding the smallest program that demonstrates the error" is a powerful debugging tool.
    Look up a C++ Reference and learn How To Ask Questions The Smart Way

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    C++ Developer XSquared's Avatar
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    Or you can look up the stringstream class.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

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    you can use sscanf() in C++, but you'll need to #include <cstdio>
    ....yes,as C++ is a superset of C. but that will not be pure C++ programming....it will be mixed thing(although no error).


    actually, i was thinking a C code

    fgets(buff,100,ptr) // it is similar to getline() in C++
    sscanf( buff,"%d %d",&var1,&var2) // what is similar in C++?

    in fact in this case i was expecting similar C++ function if exist .

    thanks
    blue_gene

  5. #5
    Code Goddess Prelude's Avatar
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    >but that will not be pure C++ programming....
    Yes it will. If the C++ standard defines a construct, then it's "pure" C++. fgets and sscanf just don't conform to your idea of "pure" C++.

    >it will be mixed thing(although no error).
    And what's wrong with that? It seems to me that you're needlessly restricting yourself with this skewed concept of "pure" C++.

    >in fact in this case i was expecting similar C++ function if exist
    Pure C++ doesn't use archaic things like functions, it uses objects. If you want a one-liner, sscanf is there. Otherwise you're stuck with stringstreams:
    Code:
    string buff;
    int var1, var2;
    //fgets(buff,100,ptr) // it is similar to getline() in C++
    getline ( cin, buff );
    //sscanf( buff,"%d %d",&var1,&var2) // what is similar in C++?
    istringstream cppsscanf ( buff );
    cppsscanf>> var1 >> var2;
    My best code is written with the delete key.

  6. #6
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    Just to clarify a bit, the equivilant of sscanf(...) == 2 is to evaluate the istringstream in a boolean context, or test !fail(). Here is preludes code with a bit more error checking.
    Code:
    std::string buff;
    if(std::getline(std::cin, buff)) {
        std::istringstream iss(buff);
        int a,b;
        if(iss >> a >> b) {
            std::cout << a << ", " << b << std::endl;
        } else {
            std::cerr << '"' << iss.str() << "\" does not start with two ints\n";
            iss.clear(); // clear all errors
            char ch;
            if(iss.get(ch)) {
                std::cerr << "confused by '" << ch << "' at pos " 
                          << static_cast<int>(iss.tellg())-1 << std::endl;
            } else if(iss.eof()) {
                std::cerr << "unexpected end of file\n";
            } else { // in theory we never reach here
                std::cerr << "unrecoverable internal stream error\n";
            }
        }
    } else {
        std::cerr << "Could not read from standard input\n";
    }

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