STL string utils

STL’s std::string doesn’t have methods for transforming the string to upper or lower case or for trimming (as other string implementations, such as CString, have). I’ve noticed that many people don’t know how to implement such functions, so I’ll show you here how to do that.

class stringutils
{
public:
	static void make_upper(std::string& text)
	{
		std::transform(text.begin(), text.end(), text.begin(), toupper);
	}

	static void make_lower(std::string& text)
	{
		std::transform(text.begin(), text.end(), text.begin(), tolower);
	}

	static void trim_left(std::string& text)
	{
		if(!text.empty())
		{
			std::string::iterator pos = text.begin();
			while(pos != text.end() && isspace(*pos)) pos++;

			text.erase(text.begin(), pos);
		}
	}

	static void trim_left(std::string& text, const char* toremove)
	{
		if(!text.empty())
		{
			std::string::size_type pos = text.find_first_not_of(toremove);
			if(std::string::npos != pos) text.erase(0, pos);
			else text.clear();
		}
	}

	static void trim_right(std::string& text)
	{
		if(!text.empty())
		{
			std::string::iterator pos = text.end() - 1;
			while(pos != text.begin() && isspace(*pos)) pos--;

			text.erase(pos+1, text.end());
		}
	}

	static void trim_right(std::string& text, const char* toremove)
	{
		if(!text.empty())
		{
			std::string::size_type pos = text.find_last_not_of(toremove);
			if(std::string::npos != pos) text.erase(pos + 1);
			else text.clear();
		}
	}
};

You can use it like this:

std::string text = " \r\n sample text \r\n ";

stringutils::make_upper(text);
std::cout << text << std::endl;

stringutils::trim_left(text);
std::cout << text << std::endl;

stringutils::trim_right(" \r\n");
std::cout << text << std::endl;