存储表达式的最佳做法

Question

I'm trying to store an expression (operators and operands) in a container. The best implementation I can think of is storing them in a string.

For example:

2 30 + 5 *

would be stored as

"2 30 + 5 *"

However, this incur the problem that, when extracting from the string using

string tk;
string expr;
stringstream e(expr);
e >> tk;

if there're any missing space, "2 30+ 5*", the error handling part would be some kind of distracting. Is there any better way to do this?

Thanks.

Answer 1

无论您需要将表达式分解成多个部分（进行令牌化），都应先执行此操作，然后再存储令牌的数组/向量。