Memory leak in mpf_get_str()

[Michael Abshoff]

Carlos Carreras wrote:
>
> Hello,

Hello Carlos,


>
> I am new to this list so I dont' know if this has been discussed before.
> If I use mpf_get_str() to obtain a string with all the significant
> digits, valgrind detects a memory leak. Running 'valgrind
> --leak-check=full' after compiling the following code indicates a leak
> of 3 bytes definitely lost.
> If the initilization uses the double 2.1, the leak is of 22 bytes.
>
> #include<gmp.h>
> int main() {
>   mpf_set_default_prec(64);
>   mpf_t n;
>   mpf_init_set_si(n, -1);
>   mp_exp_t e;
>   mpf_get_str(NULL, &e, 10, 0, n);
>   mpf_clear(n);
>   return 0;
> }
>
> What am I doing wrong? How can I get around this? Thanks!

If you look at
http://gmplib.org/manual/Converting-Floats.html#Converting-Floats you will
see:

Function: char * mpf_get_str (char *str, mp_exp_t *expptr, int base,
size_t n_digits, mpf_t op)

You pass NULL as the first argument: "If str is NULL, the result string is
allocated using the current allocation function (see Custom Allocation).
The block will be strlen(str)+1 bytes, that being exactly enough for the
string and null-terminator."

So you need to clean up that char* by yourself, which is exactly the leak
that valgrinds reports.

Hope that helps,

Michael

>
> Carlos
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