LinuxQuestions.org - goto usage

- Programming (https://www.linuxquestions.org/questions/programming-9/)

- - goto usage (https://www.linuxquestions.org/questions/programming-9/goto-usage-155184/)

Quick program run down -> enter numbers, porgram does the math, porgram asks user if they would like to do it again.
However it doesn't work. I think I'm using goto wrong but have not found much of anything thats helpfull.

Code:



#include <iostream.h>



#include <math.h>



int main ()



{



    float A ;

    float B ;

    float C ;

    int equation ;

    float answer ;

    int Repeat;



//Asking for all required inputs



    cout <<"By inputing 1 you are using the -B '-'..., by inputing 2 you are using/n";

    cout <<"-B'+'... for the equation/n";



    loop:

    cout <<"Is the equation for x1 or x2?";

    cin >> equation;

    cout <<"Enter the value for A ";

    cin >> A;

    cout <<"Enter the Value for B ";

    cin >> B;

    cout <<"Enter the Value for C " ;

    cin >> C;



// doin the math, depending on user input



//I know the math is worng, but I will come to that in time

    if (equation == '1')



        {



                answer = (-B - sqrt((B*B) - 4*A*C)/(2*A)) ;



        }



    if (equation == '2')



        {



                answer = (-B + sqrt((B*B) - 4*A*C)/(2*A)) ;



        }



    cout <<"The root of you input of " << equation <<" is "<< answer << endl;

    cout <<"You input " << A << " for A\n";

    cout <<"You input " << B << " for B\n";

    cout <<"You input " << C << " for C\n";



    cout <<"Would you like to do another equation?";

    cin >> Repeat;



//Repeating upon the users request



// This is  my goto attempt



    if (Repeat == 'Y' || Repeat == 'y')



        {



                goto loop;



        }



    if (Repeat == 'N' || Repeat == 'n')



        {



                return(0);



        }



}

-Thanks in advance

Why don't you put the stuff that gets called over and over in a seperate function, have that function return a char (the response to "would you like to continue"). And then have your main loop do something like this:

repeat = loop();
while((repeat == 'y') || (repeat == 'Y")) {
repeat=loop();
}

goto's are consider by most to be terrible programming form in C/C++.

In case I didn't make myself clear... this works:

Code:

#include <iostream>



#include <math.h>

char loop();



int main()

{

    char Repeat;

    Repeat = loop();

    while((Repeat == 'y') || (Repeat == 'Y')) Repeat = loop();

    return 0;

}



char loop()

{

    float A;

    float B;

    float C;

    int equation;

    float answer;

    char Repeat;



  //Asking for all required inputs



    std::cout << "By inputing 1 you are using -B '-'...\n";

    std::cout << "By inputing 2 you are using -B '+'...\n for the equation\n";



    std::cout << "Is the equation for x1 or x2?";

    std::cin >> equation;

    std::cout << "Enter the value for A ";

    std::cin >> A;

    std::cout << "Enter the Value for B ";

    std::cin >> B;

    std::cout << "Enter the Value for C ";

    std::cin >> C;



    // doin the math, depending on user input



    //I know the math is worng, but I will come to that in time

    if (equation == '1')

    {

      answer = (-B - sqrt((B * B) - 4 * A * C) / (2 * A));

    }



    if (equation == '2')

    {

      answer = (-B + sqrt((B * B) - 4 * A * C) / (2 * A));

    }



    std::cout << "The root of you input of " << equation << " is " << answer << "\n";

    std::cout << "You input " << A << " for A\n";

    std::cout << "You input " << B << " for B\n";

    std::cout << "You input " << C << " for C\n";



    std::cout << "Would you like to do another equation?";

    std::cin >> Repeat;

    return Repeat;

}

Btw, you might need to change #include <iostream> to #include <iostream.h> and get ride of all the std:: I added. I added these so the code would work with GCC's c++ compiler.

thanks jtshaw.,

P.S. I use the GCC compiler but never have any problems using #include<iostream.h> but thanks for the tip.

Ya, with newer versions of gcc and the -Wall option you might get a message like this:

warning: #warning This file includes at least one deprecated or antiquated header. Please consider using one of the 32 headers found in section 17.4.1.2 of the C++ standard. Examples include substituting the <X> header for the <X.h> header for C++ includes, or <sstream> instead of the deprecated header <strstream.h>. To disable this warning use -Wno-deprecated.

That is why I knocked off the .h. The new way of doing C++ you don't put the extension.
math.h is a C header which is why you keep the .h there.

syntax of goto:

{
/* some code */
loop:
/* some more code */
goto loop:
}