This is a simple inline implementation of the GNU functions asprintf() and vasprintf(). This header requires only a conforming C99 (or higher) compiler and standard library.
The usage is identical to your system's sprintf() and vsprintf(), respectively, except that the first argument is a pointer to a pointer to char, rather than a pointer directly to a char buffer. On a successful call, a new buffer large enough to hold the resulting string is allocated and assigned through the first parameter. This buffer must be passed to free() to avoid memory leaks.