How to initialize default float values in to array of structs?

Question

i have this bits of code :

typedef struct {
    kiss_fft_scalar r;
    kiss_fft_scalar i;
}kiss_fft_cpx;

kiss_fft_cpx* spectrum;
spectrum = (kiss_fft_cpx*)malloc( sizeof(kiss_fft_cpx)* 2024);

how to inialize both r and i members to 0? without looping all the array? and keep it cross platform .

use calloc instead of malloc? Depending on kiss_fft_scalar type calloc byte 0 will map to the kiss_fft_scalar 0 value (with normal float and double that is OK). — Klamer Schutte, Dec 08 '14 at 22:03
`calloc` or Fill the memory with zeros: `memset(spectrum, 0, sizeof(kiss_fft_cpx));` — Eugene Sh., Dec 08 '14 at 22:04

score 3 · Accepted Answer · edited May 23 '17 at 12:21

Portably:

for ( size_t i = 0; i < 2024; ++i )
    spectrum[i].i = spectrum[i].r = 0;

Others have suggested using calloc or memset; those will only work if you know you are only coding for a platform that uses a floating point representation in which all-bits-zero means 0.f, such as IEEE754. (I'm assuming that kiss_fft_scalar is float as your title suggests).

If the size is known at compile-time then you can write:

kiss_fft_cpx spectrum[2024] = { 0 };

which will initialize all the values to 0.

NB. Don't cast malloc and even if size is not known exactly at compile-time but known to be small, you have the option to avoid malloc/free by writing kiss_fft_cpx spectrum[size]; .

++ for the remark on the return type of `malloc()` and the suggestion of the VLA. — The Paramagnetic Croissant, Dec 08 '14 at 22:28

How to initialize default float values in to array of structs?

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