The buffer to write the formatted string into. Unlike the sformat overloads, the buffer won't be extended. This leads to a slightly different semantic for this buffer (the others are only appended to, this one is written to).
Format string to use
Variadic arguments to format according to fmt
A reference to buffer
Write the processed (formatted) input into a fixed-length buffer
This function will not perform any allocation. If the output does not fit in buffer, the extra output will simply be discarded.