Question

我想我正在宣布一切正确但我在main.cpp的第22-26行中获得了未声明的标识符。我也得到这个=在我的employee.cpp第12-16行中含糊不清。我还有一个奇怪的表达式必须有一个指向employee.cpp第55行的工资对象类型的指针。我真的很感激任何帮助，因为我的学校目前没有导师。

//Employee.h

using namespace std;

class Employee {
private:
public:
    string FirstName;
    string LastName;
    string DisplayFirstName;
    string DisplayLastName;
    string DisplaySalary;
    string SearchName;
    float Salary;
    Employee( string FirstName, string LastName, float Salary )
    {
            setFirstName(FirstName);
            setLastName(LastName);
            setSalary(Salary);
    }
    string setFirstName(string FirstName);
    string setLastName(string LastName);
    float setSalary(float Salary);
    void ReadFile(ifstream& MyinFile, string FirstName, string LastName, float Salary);
    string EmployeeSearch(string LastName[], string SearchName);
    void DisplayEmployee (string DisplayFirstName, string DisplayLastName, string DisplaySalary);
    Employee();
};

//Employee.cpp

#include <iostream>
#include <fstream>
#include <string>
#include "Employee.h"

using namespace std;

string setFirstName(string FirstName)
{
**FirstName = NULL;** //ambiguous error
}
string setLastName(string LastName)
{
**LastName = NULL;** //ambiguous error
}
float setSalary(float Salary)
{
Salary = 0.0;
}
void ReadFile(ifstream& MyinFile, string FirstName, string LastName, float Salary)
{
char exit_char;
int MaxSize;
int count = 0;

MyinFile.open("employee.dat"); 
    if (!MyinFile)
    {    //no
        cout << "Can't open input file." << endl; //Tests the right file.
        char exit_char;                         //End Program
        cout << "Press any key to exit" << endl;
        cin >> exit_char;
    }
    for(count = 0; count < MaxSize; count++)
    {
        MyinFile >> LastName[count];
        MyinFile >> FirstName[count];
        MyinFile >> **Salary[count];** //error
    }
MyinFile.close();
}
string EmployeeSearch(string LastName[], string FirstName[], float Salary, string SearchName, string DisplayFirstName, string DisplayLastName, string DisplaySalary)
{
    cout << "Please enter the name of the employee you would like to search." <<  endl;
    cin >> SearchName;

    for (int i = 0; i < 10; i++ )
    {
        if (LastName[i] == SearchName)
    {
        DisplayFirstName = FirstName[i];
        DisplayLastName = LastName[i];
        DisplaySalary = **Salary[i];**  //error
    }
    else 
        cout << "Could not find employee." << endl;
    }
};
void DisplayEmployee (string DisplayFirstName, string DisplayLastName, string DisplaySalary)
{
cout << DisplayFirstName << "   ";
cout << DisplayLastName << "    ";
cout << DisplaySalary << endl;
};

//Main.cpp
#include <iostream>
#include <fstream>
#include <string>
#include "Employee.h"

using namespace std;

const int MaxSize = 100;

int main()
{
char Redo;          //Input a character to redo the program
ifstream MyinFile;
cout << "Your Salary Machine\n\n";
Employee  Employee;
Employee.ReadFile(**MyinFile, FirstName, LastName, Salary**); //undeclared identifier error
do
{
    Employee.EmployeeSearch(**LastName[], SearchName**); //undeclared identifier error
    Employee.DisplayEmployee(**DisplayFirstName,DisplayLastName,DisplaySalary**); //undeclared identifier error
    //Asks user if they want redo the program
    cout << "Would you like to redo the program?\n";
    cout << "Please enter Y or N: \n";
    cin >> Redo;
}while(Redo == 'Y' || Redo == 'y');

return 0;
}

编写程序是为了读取一个名字和姓氏的文件然后能够输入文件中任何人的姓氏，它将显示名称和工资，然后重复。我想使用构造函数将名字和姓氏初始化为NULL，然后将工资初始化为0.0。我也应该使用get和set成员函数。

以下是错误：

------ Build started: Project: Lab3Project, Configuration: Debug Win32 ------
Main.cpp
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(22): error C2065: 'FirstName' : undeclared identifier
 \\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(22): error C2065: 'LastName' : undeclared identifier
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(22): error C2065: 'Salary' : undeclared identifier
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(25): error C2065: 'SearchName' : undeclared identifier
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(25): error C3861: 'LastName': identifier not found
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(26): error C2065: 'DisplayFirstName' : undeclared identifier
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(26): error C2065: 'DisplayLastName' : undeclared identifier
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\main.cpp(26): error C2065: 'DisplaySalary' : undeclared identifier

Employee.cpp
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\employee.cpp(12): error C2593: 'operator =' is ambiguous
      c:\program files\microsoft visual studio 10.0\vc\include\xstring(772): could be  'std::basic_string<_Elem,_Traits,_Ax> &std::basic_string<_Elem,_Traits,_Ax>::operator =(_Elem)'
      with
      [
          _Elem=char,
          _Traits=std::char_traits<char>,
          _Ax=std::allocator<char>
      ]
      c:\program files\microsoft visual studio 10.0\vc\include\xstring(767): or       'std::basic_string<_Elem,_Traits,_Ax> &std::basic_string<_Elem,_Traits,_Ax>::operator =(const _Elem *)'
      with
      [
          _Elem=char,
          _Traits=std::char_traits<char>,
          _Ax=std::allocator<char>
      ]
      while trying to match the argument list '(std::string, int)'
 \\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\employee.cpp(16): error C2593: 'operator =' is ambiguous
      c:\program files\microsoft visual studio 10.0\vc\include\xstring(772): could be 'std::basic_string<_Elem,_Traits,_Ax> &std::basic_string<_Elem,_Traits,_Ax>::operator =(_Elem)'
      with
      [
          _Elem=char,
          _Traits=std::char_traits<char>,
          _Ax=std::allocator<char>
      ]
      c:\program files\microsoft visual studio 10.0\vc\include\xstring(767): or       'std::basic_string<_Elem,_Traits,_Ax> &std::basic_string<_Elem,_Traits,_Ax>::operator =(const _Elem *)'
      with
      [
          _Elem=char,
          _Traits=std::char_traits<char>,
          _Ax=std::allocator<char>
      ]
      while trying to match the argument list '(std::string, int)'
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\employee.cpp(40): error C2109: subscript requires array or pointer type
\\psf\home\documents\visual studio 2010\projects\csci112\lab3project\lab3project\employee.cpp(55): error C2109: subscript requires array or pointer type

Answer 1

看起来您需要做很多工作来改进代码。首先，您应该将所有头文件放在Employee.h上。这在您决定包含Employee.h的任何地方都很有用，它的所有头文件也将被包含在内，因此您不必再次包含它们。
在C ++中，您可以将变量定义为指针或引用。请学习指针（*指针），双指针（ ** doublepointer）之间的区别，也称为数组指针，引用（＆amp; reference）和变量（变量）。您还应该学习如何对指针（**指针）进行取消引用。
了解类，函数或变量定义与声明之间的差异。这对您当前的分配问题尤为重要。
你有一个员工班，如果你是初学者;头文件用于构造函数，析构函数，成员变量和成员函数定义。而.cpp文件用于构造函数，成员函数和非成员函数声明。大多数情况下，析构函数的声明不包含任何内容，但是这是删除指针的地方。
在C ++中，你必须管理内存，否则你的指针会出现内存泄漏。因此，无论何时定义指针（*指针），都应该在析构函数中删除它。您在头文件中缺少析构函数。你需要定义一个。
您应该像这样在头文件中定义和/或声明构造函数。实际上没有必要在构造函数中调用SetFirstName（），setLastName（），setSalary（）。这些方法只能在MAIN类中使用。要设置类成员变量，请执行此操作。
```
Employee( string FirstName, string LastName, float Salary )
this.FirstName = FirstName;
this.LastName = LastName;
this.Salary = Salary;
```
}
包含类析构函数
```
~Employee(){
}
```
您的SET函数仅用于设置成员变量，不应返回任何内容。而不是返回一个字符串，他们应该是无效的。像这样。
设置功能定义。

void setFirstName（string FirstName）;
void setLastName（string LastName）;
void setSalary（float Salary）;
定义并声明GET函数。

string getFirstName（）{return FirstName;}
string getLastName（）{return LastName;}
float getSalary（）{return Salary;}
在.cpp文件中，您应该在Employee类中定义的其他成员函数中声明您的set函数。像这样。

void Employee :: setFirstName（string FirstName）{
FirstName = FirstName;
}
void Employee :: setLastName（string LastName）{
LastName = LastName;
}
void Employee :: setSalary（float Salary）{
薪水=薪水;
}
此Readfile函数读取此格式示例的文件;第一行;约翰加里100.50，下一行; Michael Shawn 250.80等并将其存储在Employees的矢量中。

typedef std :: vector＆lt;员工＆gt; EmployeeType
EmployeeType帐户;

void ReadFile（ifstream＆amp; MyinFile，string FirstName，string LastName，float Salary）{
string st;
float n;

while（MyinFile＆gt;＆gt; st）{
this.setFirstName（ST）;
this.setLastName（MyinFile＆gt;＆gt; st）;
this.setSalary（MyinFile＆gt;＆gt; n）;
account.push_back（本）;
}
搜索员工功能。它仅按名字搜索。
您还应该了解C ++中的数组和数组指针。

string Employee :: EmployeeSearch（string LastName，string FirstName）{

cout＆lt;＆lt; “请输入您要搜索的员工的姓名。” ＆LT;＆LT; ENDL;
cin＆gt;＆gt; SearchName;
string st =“没有这样的员工”;
string s =“”;

员工*雇用;

for（int i = 0; i＆lt; account.size（）; i ++）{
雇用= account.at（i）;
if（SearchName == employ-＆gt; getFirstName（））{
std :: cout＆lt;＆lt;雇用 - > getFirstName（）＆lt;＆lt; “”＆lt;＆lt;雇用 - > getLastName（）＆lt;＆lt; “”＆lt;＆lt;雇用 - > getSalary（）＆lt;＆lt; ENDL;
st =“”;

st.append（employ.getFirstName（））;
st.append（一个或多个）;
st.append（employ.getLastName（））;
st.append（一个或多个）;

std :: ostringstream ss;
ss＆lt;＆lt; employ.getSalary（）;
string so（ss.str（））;
st.append（左右）;
返回st;
}
} 返回st;

}

Answer 2

请看main.cpp中的这一行：

Employee.ReadFile(**MyinFile, FirstName, LastName, Salary**); //undeclared identifier error

FirstName，LastName和Salary来自哪里？他们从未在int main()的范围内宣布。这就是您有未声明的标识符错误的原因。

我不确定为什么你的Employee::ReadFile成员函数会接受最后三个参数。它应该从文件中读入并设置this.FirstName等，而不是已传递给函数的参数。

这可以让你在正确的轨道上走得更远：

// In header file, replace ReadFile prototype with:
void ReadFile(ifstream& MyinFile);

// In implementation file, replace ReadFile with:

void ReadFile(ifstream& MyinFile)
{
    char exit_char;
    int MaxSize;
    int count = 0;

    MyinFile.open("employee.dat"); 
        if (!MyinFile)
        {    //no
            cout << "Can't open input file." << endl; //Tests the right file.
            char exit_char;                         //End Program
            cout << "Press any key to exit" << endl;
            cin >> exit_char;
        }
        for(count = 0; count < MaxSize; count++)
        {
            MyinFile >> this->LastName;
            MyinFile >> this->FirstName;
            MyinFile >> this->Salary;
        }
    MyinFile.close();
    }

// In main.cpp, replace the current call to Employee.ReadFile with:
Employee.ReadFile(MyinFile);

这可能无法解决您的所有问题，但这是一个开始。

将成员变量设置为null不正确

2 个答案: