c++primer 习题9.43

void readStack(stack<char> c)

{

while(!c.empty())

{

cout<<c.top();

c.pop();

}

}

 

 

 

void main()

{

stack<char> cStack;

stack<char> cStack2;//此栈用来存储括号中的内容

int lcnt=0,rcnt=0;//用来表示左右括号数目是否相等

string exp="a+b*(c+(m+n))+x";

for(string::iterator iter=exp.begin();iter!=exp.end();iter++)

{

if(*iter=='(')

lcnt++;

if(*iter!=')')

{

cStack.push(*iter);

   

}

else if(*iter==')')

{

rcnt++;

cStack2.push(*iter);//将右括号压入新栈

while(cStack.top()!='(')//将到左括号之前的元素全部弹出栈并压入新栈

{

cStack2.push(cStack.top());

cStack.pop();

}

 

cStack2.push(cStack.top());//此时老栈里面的栈顶符号应为‘（’

cStack.pop();

cStack.push('#');//代替括号的标识符

 

 }

}

 

 

if(lcnt==rcnt)

{

 

readStack(cStack);

cout<<"haha"<<endl;

readStack(cStack2);

}

else

cout<<"表达式中的左右括号数目不等";

 

}