CODEWITHSUNDEEP
c++segmentation-fault
Denys S.
Denys S.

Reputation: 6515

Segfault with same function names. Why? How to fix?

I know that by changing the trig function names I get rid of segfault. However, it is not completely clear to me why. My guess is that I get recursive calls inside my implementations. Can someone please give a rigorous explanation here?

Furthermore, I'm willing to keep things this way thus am wondering what should be added/modified to leave names of my functions as they are.

P.S.: I know it's a dumb question, just starting c++ here, so bear with me, please. :)

Code:

#include <iostream>
#include <string>
#include <cmath>

#define _USE_MATH_DEFINES

using namespace std;

/*
   Represents a calculator with various functions.
*/
class Calc {
public:
    //arithmetic functions
    static double sum(double a, double b){ return a+b; };
    static double subtract(double a, double b){ return a-b;};
    static double multiply(double a, double b){ return a*b; };
    static double divide(double a, double b){ if (b == 0) return b; return a/b; };
    static double avg(double a, double b){ return (a+b)/2; };

    //trigonometric funcitons
    static double sin(double x){ return sin(M_PI*x); };
    static double cos(double x){ return cos(M_PI*x); };
    static double tan(double x){ return tan(M_PI*x); };
};

void getValue(double *a){
    cout << "Please, enter a value: " << endl;
        cin >> (*a);
}

void getValues(double *a, double *b){
    cout << "Please, enter two values: " << endl;
        cin >> (*a) >> (*b);
}

bool getCommand(string *cmd){
    cout << "Please, enter a command (+,-,*,/,avg, sin, cos, tan, exit): ";
    cin >> (*cmd);
    if ( (*cmd) == "exit"){
        return false;
    } else {
        return true;
    }
}

int main (){
    string cmd;
    double a,b;

    while (getCommand(&cmd)){
        if (cmd == "sin" || cmd == "cos" || cmd == "tan"){
            getValue(&a);
            if (cmd == "sin"){
                cout << "Sine: " << Calc::sin(a) << endl;
            } else if (cmd == "cos"){
                cout << "Cosine: " << Calc::cos(a) << endl;
            } else if (cmd == "tan"){
                cout << "Tangent: " << Calc::tan(a) << endl;
            }
        } else {
            getValues(&a,&b);
            if (cmd == "+"){
                cout << "Summation: " << Calc::sum(a,b) << endl;
            } else if (cmd == "-"){
                cout << "Subtracttion: " << Calc::subtract(a,b) << endl;
            } else if (cmd == "*"){
                cout << "Multiplication: " << Calc::multiply(a,b) << endl;
            } else if (cmd == "/"){
                cout << "Division: " << Calc::divide(a,b) << endl;
            } else if (cmd == "avg"){
                cout << "Average: " << Calc::avg(a,b) << endl;
            }
        }
    }
    return 0;
}

Upvotes: 1

Views: 260

Answers (2)

john
john

Reputation: 87959

You got it, recursive calls. I think you want

static double sin(double x){ return ::sin(M_PI*x); };

Using the scope resolution operator :: will make your sin function call the global sin function, instead of recursively calling yours.

BTW if you are trying to convert degrees to radians then you actually need

static double sin(double x){ return ::sin((M_PI/180.0)*x); };

Upvotes: 7

Angew is no longer proud of SO
Angew is no longer proud of SO

Reputation: 171117

1) You should #define _USE_MATH_DEFINES before you #include <cmath>.

2) Your Calc functions indeed contain infinite recursion (they're calling themselves). You need to change them as follows:

static double sin(double x){ return std::sin(M_PI*x); }

That is, qualify the call to sin() to make it clear you want to call the global one.

Upvotes: 1

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