Question

for each (std::string s in m_intro.text) // std::vector<string>
    {
        for (int i = 0; i < s.length(); i++)
        {
            char* chr = &s.at(i);
            chr[i+1] = NULL;
            std::string t(chr);

            // other code is used below not shown as not relivent

        }

    }

I want to get a char from a string. Each char I get I then want to turn into a string (there is a function that needs a const std::string&)

The above code works once, but after the first loop the entire of s is null. I can see why this is happening.

What I want is to get the next char from s on each loop and store it as a string.

Answer 1

char* chr = &s.at(i);
chr[i+1] = NULL;
std::string t(chr);

When the char was part of a C-string (or char array), you used the right (if antiquated) approach of setting the next element to NULL to terminate the string.

However in this case, this is not relevant; you’re just indexing into a std::string and replacing all its characters with NULL, which is of course not what you meant.

std::string has a constructor you can use to avoid this nastiness:

std::string t(1, s.at(i));
//   ^        ^    ^
//   |        |    |
// string     |    |
//            |    |
//     of length 1 |
//        char     |
//                 |
//     each having value s.at(i)

No need to mess with pointers or char arrays or NULL-termination.