Looking at libstdc++ documentation I find (see the link for more info): A string looks like this: [_Rep] _M_length [basic_string<char>] _M_capacity _M_dataplus _M_refcount _M_p —————-> unnamed array of char_type So, yes it is ref counted. Also, from the discussion here: Yes, std::string will be made non-reference counting at some point, but as a non-reference-counted string … Read more
Consider this: std::string str = “Hello ” + “world”; // bad! Both the rhs and the lhs for operator + are char*s. There is no definition of operator + that takes two char*s (in fact, the language doesn’t permit you to write one). As a result, on my compiler this produces a “cannot add two … Read more
The pointer returned by std::string::c_str() points to memory maintained by the string object. It remains valid until a non-const function is called on the string object, or the string object is destructed. The string object you’re concerned about is a temporary. It will be destructed at the end of the full expression, not before and … Read more
#include <sstream> // st is input string int result; stringstream(st) >> result;
Use boost::algorithm::join(..): #include <boost/algorithm/string/join.hpp> … std::string joinedString = boost::algorithm::join(elems, delim); See also this question.
My point of view is: Never use char * if you don’t call “C” code. Always use std::string: It’s easier, it’s more friendly, it’s optimized, it’s standard, it will prevent you from having bugs, it’s been checked and proven to work.
Since C++14 we have been able to create literal std::string #include <iostream> #include <string> int main() { using namespace std::string_literals; std::string s = “pl-\0-op”s; // <- Notice the “s” at the end // This is a std::string literal not // a C-String literal. std::cout << s << “\n”; } Before C++14 The problem is the … Read more
In alphabetical order: std::string name = “John”; int age = 21; std::string result; // 1. with Boost result = name + boost::lexical_cast<std::string>(age); // 2. with C++11 result = name + std::to_string(age); // 3. with FastFormat.Format fastformat::fmt(result, “{0}{1}”, name, age); // 4. with FastFormat.Write fastformat::write(result, name, age); // 5. with the {fmt} library result = fmt::format(“{}{}”, … Read more
A std::string’s allocation is not guaranteed to be contiguous under the C++98/03 standard, but C++11 forces it to be. In practice, neither I nor Herb Sutter know of an implementation that does not use contiguous storage. Notice that the &s[0] thing is always guaranteed to work by the C++11 standard, even in the 0-length string … Read more
In C++11 you can use std::to_string: #include <string> std::string s = std::to_string(5); If you’re working with prior to C++11, you could use C++ streams: #include <sstream> int i = 5; std::string s; std::stringstream out; out << i; s = out.str(); Taken from http://notfaq.wordpress.com/2006/08/30/c-convert-int-to-string/