asprintf, vasprintf - print to allocated string

       For an explanation of the terms used in this section, see attributes(7).
       ┌──────────────────────────────────────────────────────────────────────┬───────────────┬────────────────┐
       │ Interface                                                            │ Attribute     │ Value          │
       ├──────────────────────────────────────────────────────────────────────┼───────────────┼────────────────┤
       │ asprintf(), vasprintf()                                              │ Thread safety │ MT-Safe locale │
       └──────────────────────────────────────────────────────────────────────┴───────────────┴────────────────┘

       The  functions  asprintf()  and  vasprintf()  are analogs of sprintf(3) and vsprintf(3), except that they
       allocate a string large enough to hold the output including the terminating null byte ('\0'), and  return
       a  pointer  to  it  via  the  first  argument.   This  pointer should be passed to free(3) to release the
       allocated storage when it is no longer needed.

       Standard C library (libc, -lc)

       asprintf, vasprintf - print to allocated string

       When successful, these functions return the number of bytes printed, just  like  sprintf(3).   If  memory
       allocation  wasn't possible, or some other error occurs, these functions will return -1, and the contents
       of strp are undefined.

free(3), malloc(3), printf(3)

Linux man-pages 6.9.1                              2024-06-15                                        asprintf(3)

       GNU, BSD.

#define_GNU_SOURCE         /* See feature_test_macros(7) */
       #include<stdio.h>intasprintf(char**restrictstrp,constchar*restrictfmt,...);intvasprintf(char**restrictstrp,constchar*restrictfmt,va_listap);

       The FreeBSD implementation sets strp to NULL on error.