Could not convert double to string - c++

Question

I've been working on a program that calculates the volume of a box, using classes to help me understand how to use classes. As part of the program I want to convert my objects length,width and height into a string to display the dimensions of the box. When I run the code from my main file it crashes. When I run it from the class file I get "could not convert Box::length from double to std::string. How can I fix the conversion error?
#include <iostream>
#include <stdexcept>
#include <sstream>
#include <iomanip>
#include <string>
using namespace std;
class Box
{
public:
double length;//length of the box
double height;//height of the box
double width;//with of the box
Box(): length(1), height(1), width(1){}
//Parameterized Constructor
Box(double length, double width, double height);
double getVolume(void);
//Mutators
void setLength(double leng);
void setWidth(double wid);
void setHeight(double hei);
//Acessors
string toString() const;
string getLength();
string getWidth();
string getHeight();
};//end class
//member function definitions
double Box::getVolume(void)//get volume will cal and output the volume when called
{
return length * width * height;
}
void Box::setLength(double leng)
{
const double MIN_LENGTH = 0.1;//constants for min/max for range check and out_of_range exception
const double MAX_LENGTH = 99;
if (length > MAX_LENGTH || length < MIN_LENGTH)
{
stringstream strOut;//declare string stream
strOut << "Length is out of range. Length must be between" << MIN_LENGTH << " and " << MAX_LENGTH << ".";//error msg
throw out_of_range(strOut.str());
}
else
{
length = leng;// if length is within range, store it
}
}
string Box::getLength()
{
return length;
}
void Box::setWidth(double wid)
{
const double MIN_WIDTH = 0.1;//constants for min/max for range check and out_of_range exception
const double MAX_WIDTH = 99;
if (length > MAX_WIDTH || length < MIN_WIDTH)
{
stringstream strOut;//declare string stream
strOut << "Width is out of range. Width must be between" << MIN_WIDTH << " and " << MAX_WIDTH << ".";//error msg
throw out_of_range(strOut.str());
}
else
{
width = wid;// width is in range, store it
}
}
string Box::getWidth()
{
return width;
}
void Box::setHeight(double hei)
{
const double MIN_HEIGHT = 0.1;//constants for min/max for range check and out_of_range exception
const double MAX_HEIGHT = 99;
if (length > MAX_HEIGHT || length < MIN_HEIGHT)
{
stringstream strOut;//declare string stream
strOut << "Height is out of range. Height must be between" << MIN_HEIGHT << " and " << MAX_HEIGHT << ".";//error msg
throw out_of_range(strOut.str());
}
else
{
height = hei;// height is in range, store it
}
}
string Box::getHeight()
{
return height;
}
string Box::toString() const
{
stringstream strOut;
strOut << "Length: " << getLength() << endl
<< "Width: " << getWidth() << endl <<
"Height: " << getHeight() << endl;
return strOut;
}

Answer 1

This compile error is occurring at the return statements of your getWidth, getHeight, getLength functions. This is because the you declared them to return a string but instead returned a width, height, and length which are doubles. The compiler sees that there is no automatic conversion from double to string.
To fix this you only need to fix the return type of the function from string to double:
double getLength();
double getWidth();
double getHeight();
I noticed one more error:
doubletostring.cpp:104:25: error: reference to non-static member function must be called
strOut << "Length: " << getLength << endl
And similar errors in the toString method. Simply convert them to function calls by adding () at the end:
strOut << "Length: " << getLength() << endl

Answer 2

Your class definition says getLength() will return a string, however your getLength() function actually returns width, which is a double. You probably meant to convert length to a string before you return it.
You could use the to_string() function in the string library, and change your getLength() to
return to_string(length)