c++将指针传递给函数

Question

我正在尝试用 C++ 创建一个控制台应用程序，提示用户输入一个 float ，然后获取该数字并将整数部分和小数部分分开。

示例输出为:-

请输入 float :
800.589
整数部分为800，小数部分为.589

我的解决方案如下所示:

#include <iostream>
#include <cmath>
using namespace std;

void spliceAnyNumber (double anyNumber)
{
double integerPart = 1;
double fractionPart = 1;
double *pIntegerPart = &integerPart;
double *pFractionPart = &fractionPart;
fractionPart = fmod(anyNumber,1);
integerPart = anyNumber - fractionPart;
cout << "The integer part is " << *pIntegerPart << " and the fraction part is " << *pFractionPart << "\n";
cout << endl;
cout << "The address of *pIntegerPart is " << &integerPart << "\n";
cout << endl;
cout << "The address of *pFractionPart is " << &fractionPart << "\n";
cout << endl;
}

int main()
{   
cout << "Please enter a floating point number: ";
double anyNumber = 0;
cin >> anyNumber;
cout << endl;    
spliceAnyNumber(anyNumber);
system("Pause");
return 0;   
}

我编写了程序，但我也被要求将指针传递给函数并操作取消引用的值。我尝试在下面这样做，但我从编译器那里得到了一堆错误。

#include <iostream>
#include <cmath>
using namespace std;

void spliceAnyNumber (double *pAnyNumber)
{
double integerPart = 1;
double fractionPart = 1;
double *pIntegerPart = &integerPart;
double *pFractionPart = &fractionPart;
&fractionPart = fmod(&anyNumber,1);
&integerPart = &anyNumber - &fractionPart;
cout << "The integer part is " << *pIntegerPart << " and the fraction part is " <<     *pFractionPart << "\n"; *pFractionPart << "\n";
cout << endl;
cout << "The address of *pIntegerPart is " << &integerPart << "\n";
cout << endl;
cout << "The address of *pFractionPart is " << &fractionPart << "\n";
cout << endl;
}

int main()
{   
cout << "Please enter a floating point number: ";
double *pAnyNumber = &anyNumber;
cin >> *pAnyNumber;
cout << endl;    
spliceAnyNumber(*pAnyNumber);
system("Pause");
return 0;   
}

添加指针哪里出错了？版本 1 有效，但版本 2 无效。

Answer 1

我已经标记了这个内联。

#include <iostream>
#include <cmath>
using namespace std;

void spliceAnyNumber (double *pAnyNumber)
{
  double integerPart = 1;
  double fractionPart = 1;
  double *pIntegerPart = &integerPart;
  double *pFractionPart = &fractionPart;
  &fractionPart = fmod(&anyNumber,1);  // <- you should dereference pAnyNumber instead, and assign to fractionPart (i.e. "fractionPart = fmod(*pAnyNymber, 1);
  &integerPart = &anyNumber - &fractionPart;  // <- similar as above
  cout << "The integer part is " << *pIntegerPart << " and the fraction part is " <<     *pFractionPart << "\n"; *pFractionPart << "\n";
  cout << endl;
  cout << "The address of *pIntegerPart is " << &integerPart << "\n";
  cout << endl;
  cout << "The address of *pFractionPart is " << &fractionPart << "\n";
  cout << endl;
}

int main()
{   
  cout << "Please enter a floating point number: ";
  double *pAnyNumber = &anyNumber;  // <- you haven't declared an 'anyNumber' variable to take the address of
  cin >> *pAnyNumber;
  cout << endl;    
  spliceAnyNumber(*pAnyNumber);
  system("Pause");
  return 0;   
}