C++ Remove new line from multiline string

Slight modification on edW's solution to remove all exisiting endline chars

void chomp(string &s){
size_t pos;
while (((pos=s.find('\n')) != string::npos))
    s.erase(pos,1);
}

Note that size_t is typed for pos, it is because npos is defined differently for different types, for example, -1 (unsigned int) and -1 (unsigned float) are not the same, due to the fact the max size of each type are different. Therefore, comparing int to size_t might return false even if their values are both -1.

To extend @Greg Hewgill's answer for C++11:

If you just need to delete a newline at the very end of the string:

This in C++98:

if (!s.empty() && s[s.length()-1] == '\n') {
    s.erase(s.length()-1);
}

...can now be done like this in C++11:

if (!s.empty() && s.back() == '\n') {
    s.pop_back();
}

Optionally, wrap it up in a function. Note that I pass it by ptr here simply so that when you take its address as you pass it to the function, it reminds you that the string will be modified in place inside the function.

void remove_trailing_newline(std::string* str) 
{
    if (str->empty())
    {
        return;
    }

    if (str->back() == '\n') 
    {
        str->pop_back();
    }
}

// usage
std::string str = "some string\n";
remove_trailing_newline(&str);

Whats the most efficient way of removing a 'newline' from a std::string?

As far as the most efficient way goes--that I'd have to speed test/profile and see. I'll see if I can get back to you on that and run some speed tests between the top two answers here, and a C-style way like I did here: Removing elements from array in C. I'll use my nanos() timestamp function for speed testing.

Other References:

1. See these "new" C++11 functions in this reference wiki here: https://en.cppreference.com/w/cpp/string/basic_string
2. https://en.cppreference.com/w/cpp/string/basic_string/empty
3. https://en.cppreference.com/w/cpp/string/basic_string/back
4. https://en.cppreference.com/w/cpp/string/basic_string/pop_back