std::string formatting like sprintf

Question

I have to format std::string with sprintf and send it into file stream. How can I do this?

Answer 1

I usually use this:

std::string myformat(const char *const fmt, ...)
{
        char *buffer = NULL;
        va_list ap;

        va_start(ap, fmt);
        (void)vasprintf(&buffer, fmt, ap);
        va_end(ap);

        std::string result = buffer;
        free(buffer);

        return result;
}

Disadvantage: not all systems support vasprint