我每次在Visual Studio上都会收到相同的错误消息 . 我不知道错误源自何处 . 基本上我正在尝试使用堆栈将中缀表达式（A B-C）转换为后缀表达式（AB C-） . 任何帮助将不胜感激
DriverExpression.cpp Expression.obj：错误LNK2019：未解析的外部符号“public：__thiscall stackType :: stackType（int）”（?? 0？$ stackType @ D @@ QAE @ H @ Z）在函数“public：void”中引用__thiscall Expression :: convertInfixToPostfix（void）“（？convertInfixToPostfix @ Expression @@ QAEXXZ）Expression.obj：错误LNK2019：未解析的外部符号”public：__thiscall stackType :: ~clipType（void）“（?? 1？$ stackType @ D @@ QAE @XZ）在函数“public：void __thiscall Expression :: convertInfixToPostfix（void）”中引用（？convertInfixToPostfix @ Expression @@ QAEXXZ）Expression.obj：错误LNK2019：未解析的外部符号“public：char __thiscall stackType :: top （void）const“（？top @？$ stackType @ D @@ QBEDXZ）在函数”public：void __thiscall Expression :: convertInfixToPostfix（void）“中引用（？convertInfixToPostfix @ Expression @@ QAEXXZ）Expression.obj：错误LNK2019：未解析的外部符号“public：void __thiscall stackType :: initializeStack（void）”（？initializeStack @？$ stackType @ D @@ QAEXXZ）参考d in function“public：void __thiscall Expression :: convertInfixToPostfix（void）”（？convertInfixToPostfix @ Expression @@ QAEXXZ）Expression.obj：error LNK2019：unresolved external symbol“public：bool __thiscall stackType :: empty（void）const”（ ？empty @？$ stackType @ D @@ QBE_NXZ）在函数“public：void __thiscall Expression :: convertInfixToPostfix（void）”中引用（？convertInfixToPostfix @ Expression @@ QAEXXZ）Expression.obj：错误LNK2019：未解析的外部符号“public： void __thiscall stackType :: push（char）“（？push @？$ stackType @ D @@ QAEXD @ Z）在函数”public：void __thiscall Expression :: convertInfixToPostfix（void）“中引用（？convertInfixToPostfix @ Expression @@ QAEXXZ） Expression.obj：错误LNK2019：未解析的外部符号“public：void __thiscall stackType :: pop（void）”（？pop @？$ stackType @ D @@ QAEXXZ）在函数“public：void __thiscall Expression :: convertInfixToPostfix”中引用（void ）“（？convertInfixToPostfix @ Expression @@ QAEXXZ）C：\ Users \ Jake Bock \ Desktop \ CSC 240 \ Project 7 \ JBock_Project 7 \ Debug \ JBock_Project7.exe：致命错误LNK1120：7个未解析的外部**
#include <iostream>
#include <fstream>
#include <string>
#include <stack>
#include "Expression.h"
#include "stackType.h"
using namespace std;
int main()
{
string fileName;
string infixExpression, postfixExpression;
Expression expression;
cout << "Converting infix expression to postfix expression\n"
<< "testing infix expressions are in input file\n";
cout << "Enter the input file name ";
cin >> fileName;
ifstream inData;
ofstream outData;
inData.open(fileName.c_str());
outData.open("out.txt");
cout<<"open="<<fileName<<endl; //debugging print
while(inData>>infixExpression)
{
cout<<"Infix="<<infixExpression<<endl; //debugging print
expression.setInfix(infixExpression);
cout<<"setInfix="<<infixExpression<<endl;//debugging print
expression.convertInfixToPostfix();
cout<<"convert="<<infixExpression<<endl; //debugging print
postfixExpression = expression.getPostfix();
cout << "Infix Expression: "
<< infixExpression <<"\n"
<< "Postfix Expression: "
<<postfixExpression<<"\n\n";
outData << "Infix Expression: "
<< infixExpression <<"\n"
<< "Postfix Expression: "
<<postfixExpression<<"\n\n";
}
inData.close();
outData.close();
system("pause");
return 0;
}
================================================== ==============
#ifndef EXPRESSION_H_
#define EXPRESSION_H_
#include "stackType.h"
class Expression
{
private:
std::string infixExpression;
std::string postfixExpression;
bool precedence(char s, char operator2); //ToDo
bool isOperand(char symbol); //ToDo
public:
Expression();
void setInfix(std::string infix);
std::string getInfix();
std::string getPostfix();
void convertInfixToPostfix(); //ToDo
static void convertInfixToPostfix( //ToDo
std::string& infix,
std::string& postfix);
virtual ~Expression();
};
#endif /* EXPRESSION_H_ */
#include <stack>
#include <string>
#include <sstream>
#include "Expression.h"
#include "stackType.h"
#include <iostream>
using namespace std;
Expression::Expression() : infixExpression(""), postfixExpression(""){}
void Expression::setInfix(string infix)
{
infixExpression= infix;
}
string Expression::getInfix()
{
return infixExpression;
}
string Expression::getPostfix()
{
return postfixExpression;
}
void Expression::convertInfixToPostfix()
{
/*Define operator stack*/
stackType<char> s(infixExpression.size());
s.initializeStack();
ostringstream strstream;
int operand = 0;
/*String stream will help us pushing integer to our stream easily.
This is similar to sprintf(), but with less hassles.*/
int size = infixExpression.size();
int iter = 0;
for (; iter < size; ++iter)
{
switch (infixExpression[iter])
{
case '+':
case '-':
case '/':
case '*':
{
if (s.empty())
{
/*We always push the first operator*/
s.push(infixExpression[iter]);
}
else
{
/*if precedence of current operator is higher than
one on top of the stack, we simply push the current
operator to the top of the stack*/
if (precedence(s.top(), infixExpression[iter]))
{
s.push(infixExpression[iter]);
}
else
{
/*Pop from the stack and append it to string stream.
Repeat it unless we find an operator on top of the stack
whose precedence is lower or stack is empty.*/
do
{
strstream << s.top() << ' ';
s.pop();
}while (!s.empty() && !precedence(s.top(), infixExpression[iter]));
/*Now push the current operator to the stack*/
s.push(infixExpression[iter]);
}
}
break;
}
case ' ':
{
break;
}
default:
{
while (iter < size && infixExpression[iter] >= '0' && infixExpression[iter] <= '9')
{
operand = operand * 10 + (infixExpression[iter]-'0');
++iter;
}
strstream << operand << ' ';
operand = 0;
--iter;
break;
}
}
}
/*Pop one by one from operator stack and append it to our stream*/
while(!s.empty())
{
strstream << s.top() << ' ';
s.pop();
}
/*Get the string associated with our string stream*/
postfixExpression = strstream.str();
}
bool Expression::precedence(char s, char operator_specified)
{
if ((operator_specified == '+') || (operator_specified == '-'))
return false;
char top_operator = s;
if ((top_operator == '+') || (top_operator == '-'))
return true;
else
return false;
}
Expression::~Expression()
{
}
// ================================================ =======================================
#ifndef STACKTYPE_H_
#define STACKTYPE_H_
template <class T>
class stackType
{
private:
int maxStackSize;
int stackTop;
char *list;
void copyStack(const stackType& otherStack);
public:
stackType();
stackType(int stackSize);
~stackType();
char top() const;
void initializeStack();
bool empty() const;
void push(const char newItem);
bool isFullStack() const;
void pop();
const stackType& operator=(const stackType& otherStack);
};
#endif /* stackType_H_ */
#include "stackType.h"
#include <stack>
#include <cassert>
template <class T>
stackType<T>::stackType(){}
template <class T>
stackType<T>::stackType(int stackSize)
{
if (stackSize <= 0)
{
cout << "Size of the array to hold the stack must be positive" << endl;
cout << "Creating an array of size 100" << endl;
maxStackSize = 100;
}
else
maxStackSize = stackSize;
stackTop = 0;
list = new char[maxStackSize];
}
template <class T>
stackType<T>::~stackType()
{
delete [] list;
}
template <class T>
char stackType<T>::top() const
{
assert(stackTop != 0);
return list[stackTop - 1];
}
template <class T>
void stackType<T>::initializeStack()
{
stackTop = 0;
}
template <class T>
bool stackType<T>::empty() const
{
return (stackTop == 0);
}
template <class T>
bool stackType<T>::isFullStack() const
{
return (stackTop == maxStackSize);
}
template <class T>
void stackType<T>::pop()
{
if (!isEmptyStack())
stackTop--;
else
cout << "Cannot remove from an empty stack" << endl;
}
template <class T>
void stackType<T>::push(const char newItem)
{
if (!isFullStack())
{
list[stackTop] = newItem;
stackTop++;
}
else
cout << "Cannot add to a full stack" << endl;
}
template <class T>
void stackType<T>::copyStack(const stackType& otherStack)
{
delete [] list;
maxStackSize = otherStack.maxStackSize;
stackTop = otherStack.stackTop;
}
template <class T>
const stackType<T>& stackType<T>::operator=(const stackType& otherStack)
{
if (this != &otherStack)
copyStack(otherStack);
return *this;
}
2 回答
unresolved external symbol好的，所以你在这里遇到了链接器错误 . 每当你得到它，这是解决它的过程 . 首先，让我们看看错误消息 .
public: __thiscall stackType::stackType(int)" (??0?$stackType@D@@QAE@H@Z) referenced in function "public: void __thiscall Expression::convertInfixToPostfix(void)" (?convertInfixToPostfix@Expression@@QAEXXZ)现在发生了什么是你的方法（在这种情况下，一个构造函数）被声明但从未定义 . 所以，仔细阅读清单......
stackType.cpp是否包含在您的构建中？
你还记得在.cpp文件中编写stackType :: stackType（int）吗？
这两个函数的方法签名是否相同？你有一个const方法而另一个没有吗？
类或方法名称中的任何奇怪的拼写错误？
你做错了涉及模板吗？
我的猜测是＃4是罪魁祸首，因为stackType是一个模板类 . 您需要将所有这些方法定义粘贴到 Headers 中，可能不是 .
所以问题出来了我只需要在头文件中保留模板类成员函数定义 . Oy公司 .