fmt_double - Man Page

#include <fmt.h>

size_t fmt_double(char *dest,double d,size_t maxlen,size_t prec);

fmt_double writes an ASCII representation ('0' to '9', base 10) of d to dest and returns the number of bytes written.  No more than maxlen bytes will be written.  prec digits will be written, using scientific notation if necessary.

fmt_double does not append \0.

If dest equals FMT_LEN (i.e. is zero), fmt_double returns the number of bytes it would have written.

scan_double(3)