This function is similar to sprintf
, except that it dynamically
allocates a string (as with malloc
; see Unconstrained Allocation) to hold the output, instead of putting the output in a
buffer you allocate in advance. The ptr argument should be the
address of a char *
object, and asprintf
stores a pointer
to the newly allocated string at that location.
The return value is the number of characters allocated for the buffer, or
less than zero if an error occurred. Usually this means that the buffer
could not be allocated.
Here is how to use asprintf
to get the same result as the
snprintf
example, but more easily:
/* Construct a message describing the value of a variable
whose name is name and whose value is value. */
char *
make_message (char *name, char *value)
{
char *result;
if (asprintf (&result, "value of %s is %s", name, value) < 0)
return NULL;
return result;
}