大家看看这个问题怎么解决

#刚开始学数据结构，我希望能计算实数范围内的表达式求值，结果出现这样报错，但能计算出正确结果

‘#pragma once
#define ERROR 0
#define OK 1
#define EMPTY 0
template<class T>
struct Node {
    T data;
    Node<T>* next;
};
template<class T>
class Stack {
    Node<T>* top;
public:
    Stack();
    virtual ~Stack();
    int Push(T e);
    int Pop(T& e);
    int GetTop(T& e);
    int IsEmpty();
};
char Precede(char a, char b);
double Operator(double a, char c, double b);
double EvalExpr(char* exp);’

'#include"Expr.h"
#include<iostream>
#include<cmath>
using namespace std;
template<class T>
Stack<T>::Stack() {
    top = new Node<T>;
    top->next = NULL;
}
template<class T>
Stack<T>::~Stack() {
    Node<T>* p;
    while (top) {
        p = top;
        top = top->next;
        delete p;
    }
}
template<class T>
int Stack<T>::Push(T e) {
    Node<T>* p = new Node<T>;
    if (!p)    return ERROR;
    p->data = e;
    p->next = top->next;
    top->next = p;
    return OK;
}
template<class T>
int Stack<T>::Pop(T& e) {
    Node<T>* p;
    if (top->next == NULL)
        return ERROR;
    p = top->next;
    e = p->data;
    top->next = p->next;
    delete p;
    return OK;
}
template<class T>
int Stack<T>::GetTop(T& e) {
    if (top->next == NULL)
        return ERROR;
    e = top->next->data;
    return OK;
}
template<class T>
int Stack<T>::IsEmpty() {
    if (top)
        return OK;
    return EMPTY;
}
char Precede(char a, char b) {
    char PriorTable[7][7] = {
        {'>','>','<','<','<','>','>'},
        {'>','>','<','<','<','>','>'},
        {'>','>','>','>','<','>','>'},
        {'>','>','>','>','<','>','>'},
        {'<','<','<','<','<','=',' '},
        {'>','>','>','>','>','>','>'},
        {'<','<','<','<','<',' ','='}
    };
    int x = -1, y = -1;
    char opr[] = "+-*/()=";
    for (int i = 0; i < 7; i++) {
        if (a == opr[i]) x = i;
        if (b == opr[i]) y = i;
    }
    return PriorTable[x][y];
}
double Operator(double a, char c, double b) {
    switch (c) {
    case'+':return a + b;
    case'-':return a - b;
    case'*':return a * b;
    case'/':return a / b;
    default:return ERROR;
    }
}
double EvalExpr(char* exp) {
    Stack<char>OPTR;
    OPTR.Push('=');
    Stack<double>OPND;
    char op, c, theta, x;
    double a, b;
    double n = 0,f=0;
    int i,temp=0,j=1,k=0;
    c = *exp++;
    OPTR.GetTop(op);
    while (c != '=' || op != '=') {
        cout  << exp <<' '<<c << endl;
        if (c >= '0' && c <= '9') {
            k = 1;
            if (temp == 0) {
                n = n * 10 + c - '0';
                c = *exp++;
            }
            else {
                i=c - '0';
                f = i;
                n= n+f * pow(10, -temp);
                temp++;
                c = *exp++;
            }
        }
        else if (k == 0 && c == '-') {
            j = -j;
            c = *exp++;
        }
        else if (c == '.') {
            temp =1;
            c = *exp++;
        }
        else {
            if (n != 0) {
                n = n * j;
                cout << n << endl;
                OPND.Push(n);
                n = 0;
                f = 0;
                temp = 0;
                j = 1;
                k = 1;
            }
            switch (Precede(op, c)) {
            case'<':
                OPTR.Push(c);
                k = 0;
                c = *exp++;
                break;
            case'=':
                OPTR.Pop(x);
                c = *exp++;
                break;
            case'>':
                OPTR.Pop(theta);
                OPND.Pop(b);
                OPND.Pop(a);
                cout << a << theta <<  b << endl;
                OPND.Push(Operator(a, theta, b));
                break;
            }
        }
        OPTR.GetTop(op);
    }
    OPND.GetTop(a);
    return a;
}'

'
#include<iostream>
using namespace std;
#include"Expr.h"
int main() {
    char* ptr = new char;
    cout << "请输入要求值的表达式" << endl;
    cin >> ptr;
    cout << EvalExpr(ptr);
    return 0;
}'

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