C++ Remove new line from multiline string

Question

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

Answer 1

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);
    }

Answer 2

Use std::algorithms. This question has some suitably reusable suggestions Remove spaces from std::string in C++

Answer 3

The code removes all newlines from the string str.

O(N) implementation best served without comments on SO and with comments in production.

unsigned shift=0;
for (unsigned i=0; i<length(str); ++i){
    if (str[i] == '\n') {
        ++shift;
    }else{
        str[i-shift] = str[i];
    }
}
str.resize(str.length() - shift);

Answer 4

#include <algorithm>
#include <string>

std::string str;

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

The behavior of std::remove may not quite be what you'd expect. See an explanation of it here.

Answer 5

About answer 3 removing only the last \n off string code :

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

Will the if condition not fail if the string is really empty ?

Is it not better to do :

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

Answer 6

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