error：overloaded'operator<<'必须是二进制运算符（有3个参数） [英] error: overloaded 'operator<<' must be a binary operator (has 3 parameters)
问题描述
我知道有很多这样的问题，但我找不到一个适合我的解决方案。
我试图使简单分数计算器比可以添加或减去任何数量的函数，并将答案写为减少的分数。
示例：input =
3/2 + 4 /
8
，output =
2
我尝试重载运算符以完成此操作。
我试图开发输入包括一个表达式的分数由运算符'+'或' - '分隔。
表达式中的分数数是任意的。
以下6行都是有效输入表达式的示例：
1/2 + 3/4
1/2 -5 / 7 + 3/5
355/113
3 / 9-21 / -7
4 / 7-5 / -8
-2 / -3 + 7/5
*我遇到的问题是，当我运行我的程序，它有一个重载操作错误：错误：重载的操作符<<'必须是二进制运算符（有3个参数）*
/Users/Spicycurryman/Desktop/ECS40/hw1/fraction.cpp:61:22：error：overloaded 'operator'<''必须是二进制运算符（具有3个参数）
ostream& Fraction :: operator<<<（ostream& os，Fraction& n）
^
/Users/Spicycurryman/Desktop/ECS40/hw1/fraction.cpp:80:22：error：overloaded'operator> ;>'必须是二进制运算符（具有3个参数）
istream& Fraction :: operator>>（istream& os，Fraction& n）
了解为什么这是一个错误。
我的下列代码如下：
CPP FILE b
$ b
#includeFraction.h
Fraction :: Fraction（int a，int b）
{
}
int Fraction :: find_gcd（int n1，int n2）
{
int gcd，remainder;
remainder = n1％n2;
while（remainder！= 0）
{
n1 = n2;
n2 = remainder;
remainder = n1％n2;
}
gcd = n2;
return（gcd）;
}
void Fraction :: reduce_fraction（int nump，int denomp）
{
this-> nump = nump;
this-> denomp = denomp;
int gcd;
gcd = find_gcd（nump，denomp）;
nump = nump / gcd;
denomp = denomp / gcd;
if（（denomp< 0& amp; nump< 0））
{
denomp * = - 1;
nump * = - 1;
}
else if（denomp< 0& amp; nump> 0）{
denomp * = - 1;
}
if（denomp == 0）{
throw invalid_argument（Error：zero denominator）;
}
}
分数& Fraction :: operator +（const Fraction& n）{
denom = denomp * n.denom;
numera =（nump * n.numera）+（n.denom * n.nump）;
return（* this）;
}
分数& Fraction :: operator-（const Fraction& n）{
denom = denomp * n.denom;
numera =（nump * n.numera） - （n.denom * n.nump）;
return（* this）;
}
ostream& Fraction :: operator< <（ostream& os，Fraction& n）
{
if（n.numera == 0）
{
cout< 0<< endl;
return os;
}
else if（n.numera == n.denom）
{
cout< 1<< endl;
return os;
}
else
{
cout< n.numera< '/'< n.denom< endl;
return os;
}
}
istream& Fraction :: operator>>（istream& os，Fraction& n）
{
char slash = 0;
return os>> n.numera>>斜线>> ;
}
标题文件 >
#ifndef FRACTION_H
#define FRACTION_H
#include< iostream>
#include< stdexcept>
using namespace std;
class Fraction {
public：
Fraction（int a，int b）;
int fraction（int a，int b）;
int find_gcd（int n1，int n2）;
void reduce_fraction（int nump，int denomp）;
Fraction& operator +（const Fraction& n）;
Fraction& operator-（const Fraction& n）;
friend ostream& operator<<（ostream& os，const Fraction& n）;
friend istream& operator>>（istream& is，const Fraction& n）;
private：
int denom;
int numera;
int denomp;
int nump;
};
#endif
MAIN CPP FILE / p>
#includeFraction.h
#include< iostream>
using namespace std;
int main（）
{
Fraction x（2,3）;
分数y（6，-2）;
cout<< x < endl;
cout<< y < endl;
cin>> y;
cout<< y < endl;
Fraction z = x + y;
cout<< x < +<< y < =<< z < endl;
}
我知道运算符是成员函数，参数，意味着我的运算符现在需要三个参数，它可以被固定为非成员函数;然而，这不会在这个程序中工作。在我的情况下，我将如何解决它所以程序将工作？
非常感谢！
问题是作为非成员函数声明 operator>> 和运算符<，但定义为成员函数。 / p>
这应该解决这个问题（但打开另一组问题）。因此，而不是
ostream& Fraction :: operator<<（ostream& os，Fraction& n）
{
...
istream& Fraction :: operator>>（istream& os，Fraction& n）
{
...
$ b b
实现为：
ostream&运算符<<（ostream& os，Fraction& n）
{
...
istream& operator>>（istream& os，Fraction& n）
{
...
此外，请注意您声明的函数为：
朋友ostream& operator<<（ostream& os，const Fraction& n）;
friend istream& operator>>（istream& is，const Fraction& n）;
但定义为（因此您更改了签名）：
ostream& Fraction :: operator<<（ostream& os，Fraction& n）
istream& Fraction :: operator>>（istream& os，Fraction& n）
正确的方法是声明并定义为：
ostream& Fraction :: operator<<（ostream& os，const Fraction& n）
istream& Fraction :: operator>>（istream& os，Fraction& n）
我只是添加了更改。其余与问题相同：
class Fraction {
friend ostream& operator<<（ostream& os，const Fraction& n）;
friend istream& operator>>（istream& is，Fraction& n）;
//其余的是相同的
};
ostream&运算符<<<（ostream& os，const Fraction& n）
{
if（n.numera == 0）
{
cout< 0<< endl;
return os;
}
else if（n.numera == n.denom）
{
cout< 1<< endl;
return os;
}
else
{
cout< n.numera< '/'< n.denom< endl;
return os;
}
}
istream&运算符>>（istream& os，Fraction& n）
{
char slash = 0;
return os>> n.numera>>斜线>> ;
}
I know there are plenty of questions like these, but I couldn't find a solution that worked for me.
I am trying to make simple fraction calculator than can add or subtract any number of functions and write the answer as a reduced fraction.
Example: input= 3/2 + 4/ 8 , output = 2
I am trying overload operators in order to accomplish this.
So in the program, I am trying to develop the input consists of an expression made of fractions separated by the operators '+'or '-'.
The number of fractions in the expression is arbitrary.
Each of the following 6 lines is an example of valid input expression:
1/2 + 3/4
1/2 -5/7+3/5
355/113
3 /9-21/ -7
4/7-5/-8
-2/-3+7/5
*The problem that I am having is that in when I run my program it has a overload operating error: error: overloaded 'operator<<' must be a binary operator (has 3 parameters)*
/Users/Spicycurryman/Desktop/ECS40/hw1/fraction.cpp:61:22: error: overloaded 'operator<<' must be a binary operator (has 3 parameters)
ostream& Fraction::operator<<(ostream &os, Fraction& n)
^
/Users/Spicycurryman/Desktop/ECS40/hw1/fraction.cpp:80:22: error: overloaded 'operator>>' must be a binary operator (has 3 parameters)
istream& Fraction::operator>>(istream &os, Fraction& n)
I don't understand why that is an error.
My following code is below:
CPP FILE
#include "Fraction.h"
Fraction::Fraction(int a, int b)
{
}
int Fraction::find_gcd (int n1, int n2)
{
int gcd, remainder;
remainder = n1 % n2;
while ( remainder != 0 )
{
n1 = n2;
n2 = remainder;
remainder = n1 % n2;
}
gcd = n2;
return (gcd);
}
void Fraction::reduce_fraction(int nump, int denomp)
{
this->nump = nump;
this->denomp = denomp;
int gcd;
gcd = find_gcd(nump, denomp);
nump = nump / gcd;
denomp = denomp / gcd;
if ((denomp<0 && nump < 0 ))
{
denomp*=-1;
nump*=-1;
}
else if (denomp < 0 && nump >0){
denomp*=-1;
}
if ( denomp ==0) {
throw invalid_argument( "Error: zero denominator" );
}
}
Fraction& Fraction::operator+(const Fraction& n) {
denom = denomp * n.denom;
numera = (nump * n.numera) + (n.denom * n.nump);
return (*this);
}
Fraction& Fraction::operator-(const Fraction& n) {
denom = denomp * n.denom;
numera = (nump * n.numera) - (n.denom* n.nump);
return (*this);
}
ostream& Fraction::operator<<(ostream &os, Fraction& n)
{
if (n.numera == 0)
{
cout << 0 << endl;
return os;
}
else if (n.numera == n.denom)
{
cout << 1 << endl;
return os;
}
else
{
cout << n.numera << '/' << n.denom << endl;
return os;
}
}
istream& Fraction::operator>>(istream &os, Fraction& n)
{
char slash = 0;
return os >> n.numera >> slash >> n.denom;
}
Header File
#ifndef FRACTION_H
#define FRACTION_H
#include <iostream>
#include <stdexcept>
using namespace std;
class Fraction{
public:
Fraction(int a, int b);
int fraction(int a,int b);
int find_gcd(int n1, int n2);
void reduce_fraction(int nump, int denomp);
Fraction& operator+(const Fraction& n);
Fraction& operator-(const Fraction& n);
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, const Fraction& n);
private:
int denom;
int numera;
int denomp;
int nump;
};
#endif
MAIN CPP FILE
#include "Fraction.h"
#include <iostream>
using namespace std;
int main()
{
Fraction x(2,3);
Fraction y(6,-2);
cout << x << endl;
cout << y << endl;
cin >> y;
cout << y << endl;
Fraction z = x + y;
cout << x << " + " << y << " = " << z << endl;
}
I know that the operators are member functions and a member function takes an implicit first parameter, meaning my operators now takes three parameters it may be fixed being a non-member function; however, that would not work in this program. How exactly in my case would I fix it so the program would work?
Thank you very much!
The problem is that you declared operator>> and operator<< as non-member functions, but defined as a member function.
This should fix that problem (but open another set of problems). So instead of
ostream& Fraction::operator<<(ostream &os, Fraction& n)
{
...
istream& Fraction::operator>>(istream &os, Fraction& n)
{
...
implement as :
ostream& operator<<(ostream &os, Fraction& n)
{
...
istream& operator>>(istream &os, Fraction& n)
{
...
Also, take a note that you declared functions as :
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, const Fraction& n);
but defined as (therefore you changed the signature) :
ostream& Fraction::operator<<(ostream &os, Fraction& n)
istream& Fraction::operator>>(istream &os, Fraction& n)
Proper way is to declare and define as :
ostream& Fraction::operator<<(ostream &os, const Fraction& n)
istream& Fraction::operator>>(istream &os, Fraction& n)
I am adding just changes. The rest is the same as in the question:
class Fraction{
friend ostream& operator<<(ostream &os, const Fraction& n);
friend istream& operator>>(istream &is, Fraction& n);
// the rest is the same
};
ostream& operator<<(ostream &os, const Fraction& n)
{
if (n.numera == 0)
{
cout << 0 << endl;
return os;
}
else if (n.numera == n.denom)
{
cout << 1 << endl;
return os;
}
else
{
cout << n.numera << '/' << n.denom << endl;
return os;
}
}
istream& operator>>(istream &os, Fraction& n)
{
char slash = 0;
return os >> n.numera >> slash >> n.denom;
}
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