字符串中查找特定字符及该字符出现次数

[c++]代码库

// returns the index of the first occurrence of c in s
// the reference parameter occurs counts how often c occurs
string::size_type find_char(const string &s, char c, string::size_type &occurs)
{
	auto ret = s.size();	// position of the first occurrence, if any
	occurs = 0;				// set the occurrence count paramter

	for (decltype(ret) i = 0; i != s.size(); ++i)
	{
		if (s[i] == c)
		{
			if (ret == s.size())
				ret = i;	// remember the first occurrence of c

			++occurs;		// increment the occurrence count
		}
	}

	return ret;		// count is returned implicitly in occurs
}