数据结构第三章(3-3)

/*一唯数组A中保存由字母（变量），运算符（+，-，*，/）和圆括号组成的算术表达式，
圆括号允许嵌套，请编写函数，检查表达式中的括号是否配对*/
#include "iostream"
using namespace std;
enum ResultCode{Underflow,Overflow};
template
class Stack
{
public:
 virtual void Push(const T &x)=0;
 virtual void Pop()=0;
 virtual T Top() const=0;
 virtual bool IsEmpty() const=0;
 virtual bool IsFull() const=0; 
};

template
class SeqStack:public Stack
{
public:
 SeqStack(int mSize);
 ~SeqStack(){delete[] s;}
 bool IsEmpty() const {return (top==-1);}
 bool IsFull() const {return (top==maxSize-1);}
 void Push(const T &x);
 void Pop();
 T Top() const;
private:
 void Output(ostream & out)const;
 T *s;
 int maxSize;
 int top;
 friend ostream &operator<<(ostream & out,SeqStack & s);
};
template
SeqStack::SeqStack(int mSize)
{
 maxSize=mSize;
 s=new T[maxSize];
 top=-1;
}
template
void SeqStack::Pop()
{
 if(IsEmpty()) throw Underflow;
  top--;
}
template
void SeqStack::Push(const T &x)
{
 if(IsFull()) throw Overflow;
 s[++top]=x;
}
template
T SeqStack::Top() const
{
 if(IsEmpty()) throw Underflow;
 return s[top];
}
template
void SeqStack::Output(ostream& out) const
{
out<<"the stack contains:"<for(int i=top;i>-1;i--)
out<out<}
template
ostream& operator<<(ostream& out,SeqStack& s)
{
 s.Output(out);
 return out;
}
void find()
{
char str[20];
char c;
int i=0;
SeqStack seq(100);
while((c=getchar())!='\n')
{
str[i]=c;
i++;
}
try{

for(int j=0;j{
if(str[j]=='(')
seq.Push(str[j]);
else if(str[j]==')')
{
if(seq.IsEmpty()) throw Underflow;
else
seq.Pop();
}
}
cout<<"the expression is ";
}
catch(ResultCode err)
{
 switch(err)
 case Underflow:cout<<"wrong"<}
if(!seq.IsEmpty())
cout<<"wrong"<else
cout<<"right"<}
int main()
{
 find();
 return 0;
}