C++ cin/cout error


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Thread: C++ cin/cout error

  1. #1
    Join Date
    Jul 2005
    Posts
    3

    C++ cin/cout error

    I compile the following code, and get an error to do with the cin, cout operators. Basically I am trying to input parameters to a self made class using cin. However, the code does not recognise cin and cout for some reason??? :

    #define PI 3.14
    #define G 9.81;
    #include <io.h>
    #include <cmath>
    #include <iostream>
    using namespace std;

    int main (void);

    class pendulum
    { //data
    double time;
    int length;
    double velocity;
    int mass;
    int energy;

    //functions
    public:
    void run ();
    double calculate_time();
    double calculate_velocity();
    };

    double pendulum::calculate_time()
    { double input = length/G;
    time = 2*PI*sqrt(input);
    return time;
    };

    double pendulum::calculate_velocity()
    { double input = (2*energy)/mass;
    velocity = sqrt(input);
    return velocity;
    };

    void run ()
    { cout >> "time: ";
    cin >> time;
    cout >> "length: ";
    cin >> length;
    cout >> "velocity";
    cin >> velocity;
    cout >> "mass";
    cin >> mass;
    cout >> "energy";
    cin >> energy;
    };

    and get the following error:
    c:\documents and settings\vishal\my documents\visual studio 2005\projects\exercise 1\exercise 1\exercise_1.h(38) : error C2784: 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,unsigned char &)' : could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::ostream'
    C:\Program Files\Microsoft Visual Studio 8\VC\include\istream(1018) : see declaration of 'std::operator >>'
    c:\documents and settings\vishal\my documents\visual studio 2005\projects\exercise 1\exercise 1\exercise_1.h(38) : error C2784: 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,unsigned char &)' : could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::ostream'
    .... and it continues on with the same message for the rest of the cins and couts...
    ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========


    I don't understand why the code does not recognise the cin and cout operators when iostream is clrealy included? Any insights here woud be much appreciated. Thank you for your time.

  2. #2
    Join Date
    Dec 2003
    Posts
    3,366
    I dont see an error. Try explicitly calling

    cout.operator<<(variable) ; //syntax may not be 100%

    and see if that helps any.

  3. #3
    Join Date
    Aug 2003
    Posts
    313
    You have typos with the output stream operator. It should be:
    Code:
    cout << ...;
    cin >> ...;
    Hope this helps.
    ~evlich

  4. #4
    Join Date
    Nov 2003
    Posts
    4,118
    Quote Originally Posted by evlich
    You have typos with the output stream operator. It should be:
    Code:
    cout << ...;
    cin >> ...;
    Hope this helps.
    Precisely so!

    Remember: cout support <<
    cin supports >>
    Danny Kalev

  5. #5
    Join Date
    Jul 2005
    Posts
    3
    Quote Originally Posted by evlich
    You have typos with the output stream operator. It should be:
    Code:
    cout << ...;
    cin >> ...;
    Hope this helps.
    thanks problem sorted..

  6. #6
    Join Date
    Aug 2005
    Posts
    2
    the following should work for u

    #define PI 3.14
    #define G 9.81
    #include <io.h>
    #include <cmath.h>
    #include <iostream>
    //#include <conio>
    using namespace std;


    class pendulum
    { //data
    double time;
    int length;
    double velocity;
    int mass;
    int energy;

    //functions
    public:
    double calculate_time()
    {
    double input = length/G;
    time = 2*PI*sqrt(input);
    return time;
    }

    double calculate_velocity()
    {
    double input = (2*energy)/mass;
    velocity = sqrt(input);
    return velocity;
    }
    void run()
    {
    cout<<"time: ";
    cin>>time;
    cout<<"length:";
    cin>>length;
    cout<<"velocity";
    cin>>velocity;
    cout<<"mass";
    cin >> mass;
    cout <<"energy";
    cin >>energy;
    }
    };





    void main()
    {
    pendulum p;
    p.run();
    }

  7. #7
    Join Date
    Aug 2005
    Posts
    2
    yeah the problem in ur program was u did not use
    void pendulum::run()
    {
    .................
    }
    and u were terminating the function definetion using semicolon

    the following code should help u...
    [B]#define PI 3.14
    #define G 9.81
    #include <io.h>
    #include <cmath>
    #include <iostream>
    using namespace std;

    class pendulum
    { //data
    double time;
    int length;
    double velocity;
    int mass;
    int energy;

    //functions
    public:
    void run ();
    double calculate_time();
    double calculate_velocity();
    };

    double pendulum::calculate_time()
    {
    double input = length/G;
    time = 2*PI*sqrt(input);
    return time;
    }

    double pendulum::calculate_velocity()
    { double input = (2*energy)/mass;
    velocity = sqrt(input);
    return velocity;
    }

    void pendulum::run ()
    {
    cout << "time: ";
    cin >> time;
    cout << "length: ";
    cin >> length;
    cout << "velocity";
    cin >> velocity;
    cout << "mass";
    cin >> mass;
    cout << "energy";
    cin >> energy;
    }[/B]
    void main()
    {
    pendulum p;
    p.run();
    }


    regards
    maddy!

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