expressionsybol.h

C++数据结构的例子

//这个类封装了每个符号的输入和栈优先级数值

class expressionSymbol
{
public:
	expressionSymbol();
	expressionSymbol(char ch);//为运算数ch初始化对象
	friend bool operator >=(const expressionSymbol& left,const expressionSymbol& right)
	{
			return(left.stackPrecedence >=right.inputPrecedence );
	}

	char getOp() const;//返回运算符
private:
	char op;
	int inputPrecedence;//输入优先级
	int stackPrecedence;//栈优先级
};

expressionSymbol::expressionSymbol()
{
	op=' ';
}

expressionSymbol::expressionSymbol(char ch)
{
	op=ch;
}

char expressionSymbol::getOp ()const
{
	return op;
}