The functions in this section do formatted output and place the results in dynamically allocated memory.
sprintf
, except that it dynamically
allocates a string (as with malloc
; see section 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 occured. 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; }
asprintf
, except that it uses the
obstack obstack to allocate the space. See section Obstacks.
The characters are written onto the end of the current object.
To get at them, you must finish the object with obstack_finish
(see section Growing Objects).
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