C++ Primer 练习11.3.6

#include<iostream>
#include<fstream>
#include<sstream>
#include<map>
#include<string>
using namespace std;

map<string, string> buildMap(ifstream& map_file)
{
	map<string, string> trans_map;
	string key;
	string value;
	while (map_file >> key && getline(map_file, value))
		if (value.size() > 1)
			trans_map[key] = value.substr(1);
			//trans_map.insert({ key, value.substr(1) });
		else
			throw runtime_error("no rule for " + key);
	return trans_map;
}

const string&
transform(const string& s, const map<string, string>& m)
{
	auto map_it = m.find(s);
	if (map_it != m.cend())
		return map_it->second;
	else return s;
}
void word_transform(ifstream& map_file, istream& input)
{
	auto trans_map = buildMap(map_file);
	string text;
	while (getline(input, text)) {
		istringstream stream(text);
		string word;
		bool firstword = true;
		while (stream >> word) {
			if (firstword)
				firstword = false;
			else
				cout << " ";
			cout << transform(word, trans_map) << endl;
		}
	}
}
int main(int argc, char* argv[])
{
	ifstream fin("1.txt");
	word_transform(fin, cin);
	return 0;
}

1.txt:

brb be right back
k okay?
y why
r are
u you
pic picture
thk thanks!
18r later