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Em qua., 11 de nov. de 2020 às 08:23, Ranier Vilela <> escreveu:
Em ter., 10 de nov. de 2020 às 23:07, 云风 Cloud Wu <> escreveu:
Ranier Vilela <> 于2020年11月10日周二 下午9:54写道:
> Ok, I think that it was very clear.
> But C programmer shouldn't worry about filling memory with NULLs,

The point is as Andrew Gierth said , "modern compilers will
transform assignment loops into memset calls or inline implementations
of memset if circumstances suggest it will be both allowable and
efficient to do so" .

In my opinion, better C code should express the programmer's intention directly.
We need init the array with NULLs, memset is only a shallow
optimization that the compilers can do it well.
The cut took out of context.
I said "when".

And yet, in many cases, it is not necessary to initialize the array with NULLs, especially if it is a large array.
Good C codes are always defensive.

I usually code like this:
char * names[32000];

void func(names, size) {
unsigned int i;
for(i = 0; i < size; ++i) {
    if (names[i] == NULL) { /* end of array? */
   // etc etc etc

With one simple move, will reset the entire array.
Another example:

struct array {
    sizet_t size;
    size_t alloc;
    struct * mystruct[1];

ARRAY * mt;

mt->size = 0; /* reset the entire array */
void func(ARRAY * mt) {
unsigned int i;
unsigned size = mt->size; /* array length */
for(i = 0; i < size; ++i) {
   // etc etc etc
Again, with one simple move, will reset the entire array.

No need to reset with NULLs, the entire array.
Sorry, replace "unsigned int" with "size_t".

Ranier Vilela