I want to use C language to write a dynamic array dynamic array, it can automatic growth, similar to C + + STD: : vector.
Cooperate with tree, bsearch, so that I can use C language as far as possible, the following code now provide only append, remove.

Please you give more comments,

Thank you

 

//-- the dynamic array - 
#include  
#include  

Struct da_struct {
Size_t cap;//number of allocated elements 
Size_t len.//number of occupied elements 
Size_t size;//the size of an element 
Void * root;//pointer to the allocated block 
}; 

//tell the dynamic array, the element size 
Struct da_struct da_init (size_t size) {
Size_t cap=100 * 1024; 
Void * root=malloc (cap * size); 
Return (struct da_struct) {cap, 0, the size, root}; 
} 

//free the memory of the dynamic array 
Void da_cleanup (struct da_struct * da) {
Free (da - & gt; Root); 
} 

//append an object into the dynamic array 
//object size should be the same as the to the init function 
//return the element address in an array or NULL if the append fails 
Void * da_append (struct da_struct * da, void * obj) {
If (da - & gt; Len & gt;=da - & gt; Cap) {
Da - & gt; Cap *=2; 
Void * newp=realloc (da - & gt; Root, da - & gt; The size); 
if (! Newp) {
return NULL; 
} 
Da - & gt; The root=newp; 
} 

Void * PTR=da - & gt; Root + (da - & gt; Len++ - 1) * da - & gt; size; 
Memcpy (PTR, obj, da - & gt; The size); 

return ptr; 
} 

//the last element will overwrite the one to be removed 
Void * da_remove (struct da_struct * da, void * elem) {
Memcpy (elem, da - & gt; Root + da - & gt; Len - 1, da - & gt; The size); 
Return elem. 
} 

CodePudding user response:

Fine, thumb up, hope that the building Lord continue to work hard, perfect, further perfect,

CodePudding user response:

 
//diff 
- memcpy (elem, da - & gt; Root + da - & gt; Len - 1, da - & gt; The size); 
+ memcpy (elem, da - & gt; Root + - da - & gt; Len, da - & gt; The size); 

CodePudding user response:

refer to the second floor linuxusr response:

 
//diff 
- memcpy (elem, da - & gt; Root + da - & gt; Len - 1, da - & gt; The size); 
+ memcpy (elem, da - & gt; Root + - da - & gt; Len, da - & gt; The size); 

Suggest using the first, it is not recommended with a second,

First + - code attached to against reading, of course, can consider to add parentheses;
Second, with side effects, because here, although have da - & gt; Len - 1 point, at the same time, still can modify da - & gt; Len value, here to see to do not have this step, the individual feels without this step,

CodePudding user response:

reference 3 building self-confidence boy reply:

Quote: refer to the second floor linuxusr response:

 
//diff 
- memcpy (elem, da - & gt; Root + da - & gt; Len - 1, da - & gt; The size); 
+ memcpy (elem, da - & gt; Root + - da - & gt; Len, da - & gt; The size); 

Suggest using the first, it is not recommended with a second,

First + - code attached to against reading, of course, can consider to add parentheses;
Second, with side effects, because here, although have da - & gt; Len - 1 point, at the same time, still can modify da - & gt; Len value, here to see to do not have this step, the individual feels without this step,

Thank you,

This line is in the remove function, because after delete a row, to reducing the number of elements in the actual one,