Substring of char* to std::string

Question

I have an array of chars and I need to extract subsets of this array and store them in std::strings. I am trying to split the array into lines, based on finding the \n character. What is the best way to approach this?

int size = 4096;
char* buffer = new char[size];
// ...Array gets filled
std::string line;
// Find the chars up to the next newline, and store them in "line"
ProcessLine(line);

Probably need some kind of interface like this:

std::string line = GetSubstring(char* src, int begin, int end);

Answer 1

I'd create the std::string as the first step, as splitting the result will be far easier.

int size = 4096;
char* buffer = new char[size];
// ... Array gets filled
// make sure it's null-terminated
std::string lines(buffer);

// Tokenize on '\n' and process individually
std::istringstream split(lines);
for (std::string line; std::getline(split, line, '\n'); ) {
   ProcessLine(line);
}

Answer 2

You can use the std::string(const char *s, size_t n) constructor to build a std::string from the substring of a C string. The pointer you pass in can be to the middle of the C string; it doesn't need to be to the very first character.

If you need more than that, please update your question to detail exactly where your stumbling block is.