I have a lot of error with .append method in c++ - c++

Question

I have a problem with .append methon in C++.
This is my code:
#include<iostream>
#include<string>
using namespace std;
int main(){
char caratteri[] = {"ciao amici"};
string str = "ciao amici";
string token = "";
for(int i = 0; i<str.length(); i++)
{
if(str[i+1] == ' '){
token = "";
}
char current_token = str[i];
token.append(string(current_token));
i++;
}
}
And this is a part of my output:
c:\mingw\lib\gcc\mingw32\6.3.0\include\c++\bits\basic_string.h:397:7: note: no known conversion for argument 1 from 'char' to 'const std::__cxx11::basic_string<char>&'
c:\mingw\lib\gcc\mingw32\6.3.0\include\c++\bits\basic_string.h:389:7: note: candidate: std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(const _Alloc&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]
basic_string(const _Alloc& __a) _GLIBCXX_NOEXCEPT
^~~~~~~~~~~~
c:\mingw\lib\gcc\mingw32\6.3.0\include\c++\bits\basic_string.h:389:7: note: no known conversion for argument 1 from 'char' to 'const std::allocator<char>&'
c:\mingw\lib\gcc\mingw32\6.3.0\include\c++\bits\basic_string.h:380:7: note: candidate: std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string() [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]
basic_string()
^~~~~~~~~~~~
Why have I got this problem? Can I solve it?
Thank you very much :)

Answer 1

You try to create a std::string from a char here:
token.append(
string(current_token) // <- this part
);
To create a std::string from a single char, you need to supply how many times you want the char repeated:
token.append(string(1, current_token));
Fortunately, append has en overload that lets you do that directly, without creating an intermediate std::string:
token.append(1, current_token);
But the easiest would probably be to use the operator+= overload to add a single char:
token += current_token;
Note also that this
if(str[i+1] == ' ')
will access str[str.length()] when i == str.length() - 1. That is accessing it out of bounds. It will probably work anyway because there's a \0 stored just out of bounds, but I recommend that you fix that logic.