gistfile1.cpp

void tokenize(const string& instr, Tokens& tokens)
{
	// trim spaces & not valid chars
	string str;
	trim_acс trimmer(str);
	for_each(instr.begin(), instr.end(), trimmer);

	string::size_type numPos = str.find_first_of(NUMS, 0);
	string::size_type endPos = str.find_first_not_of(NUMS, numPos);
	string::size_type opPos;

	while (std::string::npos != endPos || std::string::npos != numPos)
	{
		// push number
		tokens.push_back(str.substr(numPos, endPos - numPos));

		// find & push op
		opPos = str.find_first_of(OPS, endPos);
		if (std::string::npos != opPos)
		{
			tokens.push_back(str.substr(opPos, 1));
		}

		numPos = str.find_first_of(NUMS, opPos);
		endPos = str.find_first_not_of(NUMS, numPos);
	}
}