无法将双精度转换为字符串
Could not convert double to string
我一直在开发一个计算盒子体积的程序,使用 classes 帮助我理解如何使用 classes。作为程序的一部分,我想将对象的长度、宽度和高度转换为字符串以显示盒子的尺寸。当我 运行 我的主文件中的代码崩溃时。当我从 class 文件中 运行 时,我得到“无法将 Box::length 从双精度转换为 std::string。如何修复转换错误?
#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;
}
您的 class 定义说 getLength() 将 return 一个字符串,但是您的 getLength() 函数实际上是 return 的宽度,它是一个双精度。您可能打算在 return 之前将长度转换为字符串。
您可以使用字符串库中的 to_string() 函数,并将您的 getLength() 更改为
return to_string(length)
此编译错误发生在 getWidth、getHeight、getLength 函数的 return 语句处。这是因为您将它们声明为 return 字符串,而不是 returned 宽度、高度和长度,它们是双精度的。编译器看到没有自动从double到string的转换。
要解决此问题,您只需将函数的 return 类型从字符串修复为双精度:
double getLength();
double getWidth();
double getHeight();
我注意到另一个错误:
doubletostring.cpp:104:25: error: reference to non-static member function must be called
strOut << "Length: " << getLength << endl
和 toString 方法中的类似错误。只需在末尾添加 ()
即可将它们转换为函数调用:
strOut << "Length: " << getLength() << endl
我一直在开发一个计算盒子体积的程序,使用 classes 帮助我理解如何使用 classes。作为程序的一部分,我想将对象的长度、宽度和高度转换为字符串以显示盒子的尺寸。当我 运行 我的主文件中的代码崩溃时。当我从 class 文件中 运行 时,我得到“无法将 Box::length 从双精度转换为 std::string。如何修复转换错误?
#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;
}
您的 class 定义说 getLength() 将 return 一个字符串,但是您的 getLength() 函数实际上是 return 的宽度,它是一个双精度。您可能打算在 return 之前将长度转换为字符串。
您可以使用字符串库中的 to_string() 函数,并将您的 getLength() 更改为
return to_string(length)
此编译错误发生在 getWidth、getHeight、getLength 函数的 return 语句处。这是因为您将它们声明为 return 字符串,而不是 returned 宽度、高度和长度,它们是双精度的。编译器看到没有自动从double到string的转换。
要解决此问题,您只需将函数的 return 类型从字符串修复为双精度:
double getLength();
double getWidth();
double getHeight();
我注意到另一个错误:
doubletostring.cpp:104:25: error: reference to non-static member function must be called
strOut << "Length: " << getLength << endl
和 toString 方法中的类似错误。只需在末尾添加 ()
即可将它们转换为函数调用:
strOut << "Length: " << getLength() << endl