C++ Remove new line from multiline string

Question

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

Answer 1

#include <algorithm>
#include <string>

std::string str;

str.erase(std::remove(str.begin(), str.end(), '\n'), str.cend());

The behavior of std::remove may not quite be what you'd expect.

A call to remove is typically followed by a call to a container's erase method, which erases the unspecified values and reduces the physical size of the container to match its new logical size.

See an explanation of it here.

Answer 2

If the newline is expected to be at the end of the string, then:

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

If the string can contain many newlines anywhere in the string:

std::string::size_type i = 0;
while (i < s.length()) {
    i = s.find('\n', i);
    if (i == std::string:npos) {
        break;
    }
    s.erase(i);
}

Answer 3

You should use the erase-remove idiom, looking for '\n'. This will work for any standard sequence container; not just string.

Answer 4

Here is one for DOS or Unix new line:

    void chomp( string &s)
    {
            int pos;
            if((pos=s.find('\n')) != string::npos)
                    s.erase(pos);
    }