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Error: control Reaches the completion of an unclaimed function

I am learning C ++ and I copied this code from a tutorial, compiling the code, an error appears at the end. The error says:

Management Reaches the end of a non-void function

and its location is at the end of the code:

#include "ComplexNumber.hpp"
#include <cmath>

ComplexNumber::ComplexNumber()
{
mRealPart = 0.0;
mImaginaryPart = 0.0;
}

ComplexNumber::ComplexNumber(double x, double y)
{
mRealPart = x;
mImaginaryPart = y;
}

double ComplexNumber::CalculateModulus() const
{
return sqrt(mRealPart*mRealPart+
            mImaginaryPart*mImaginaryPart);
}
double ComplexNumber::CalculateArgument() const
{
return atan2(mImaginaryPart, mRealPart);
}

ComplexNumber ComplexNumber::CalculatePower(double n) const
{
double modulus = CalculateModulus();
double argument = CalculateArgument();
double mod_of_result = pow(modulus, n);
double arg_of_result = argument*n;
double real_part = mod_of_result*cos(arg_of_result);
double imag_part = mod_of_result*sin(arg_of_result);
ComplexNumber z(real_part, imag_part);
return z;
}

ComplexNumber& ComplexNumber::operator=(const ComplexNumber& z)
{
mRealPart = z.mRealPart;
mImaginaryPart = z.mImaginaryPart;
return *this;
}

ComplexNumber ComplexNumber::operator-() const
{
ComplexNumber w;
w.mRealPart = -mRealPart;
w.mImaginaryPart = -mImaginaryPart;
return w;
}

ComplexNumber ComplexNumber::operator+(const ComplexNumber& z) const
{
ComplexNumber w;
w.mRealPart = mRealPart + z.mRealPart;
w.mImaginaryPart = mImaginaryPart + z.mImaginaryPart;
return w;
}

std::ostream& operator<<(std::ostream& output,
                     const ComplexNumber& z)
{
output << "(" << z.mRealPart << " ";
if (z.mImaginaryPart >= 0.0)
{
    output << " + " << z.mImaginaryPart << "i)";
}
else
{
    output << "- " << -z.mImaginaryPart << "i)";
}
} //-------->>>>**"Control Reaches end of non-void function"**
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3 answers

Well operator<<defined as return std::ostream&:

std::ostream& operator<<(std::ostream& output, const ComplexNumber& z)
^^^^^^^^^^^^^

but you do not have return statements, this is undefined behavior and means that you cannot rely on program behavior, the results are unpredictable. It looks like you should:

return output ;

at the end of the function. We see that this behavior is undefined from the draft of the standard C ++ section. 6.6.3Return 2 paragraph, which reads:

[...] ; undefined . [...]

+1

, -:

std::ostream& operator<<(std::ostream& output, const ComplexNumber& z)
^^^^^^^^^^^^^

return. :

return output;
+1

This function

std::ostream& operator<<(std::ostream& output,
                     const ComplexNumber& z)
{
output << "(" << z.mRealPart << " ";
if (z.mImaginaryPart >= 0.0)
{
    output << " + " << z.mImaginaryPart << "i)";
}
else
{
    output << "- " << -z.mImaginaryPart << "i)";
}
}

has a return type. std::ostream &However, it returns nothing. I think there is a typo. Must be

std::ostream& operator<<(std::ostream& output,
                     const ComplexNumber& z)
{
output << "(" << z.mRealPart << " ";
if (z.mImaginaryPart >= 0.0)
{
    output << " + " << z.mImaginaryPart << "i)";
}
else
{
    output << "- " << -z.mImaginaryPart << "i)";
}

return output;
}
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