When I want to initialize all the components of a struct I do it in the main
function like this:
This is the struct
:
typedef struct {
int data[1000];
int oc;
} Table;
And this is how I initialize all the components to be 0 (the array and the int now are 0 with this).
int main() {
Table x = {0};
Now I want to do exactly the same but using a function. I want to do something like this:
void initialize(Table *y) {
y = {0};
}
I think it does not work because to initialize it I should do it when I declare it, so how can I initialize a struct using a function?
CodePudding user response:
Remember that y
us a pointer so you must dereference it to assign the object itself.
Also you need to tell the compiler that the assignment is from a Table
object, which is done with a compound literal.
All in all:
void initialize(Table *y){
*y = (Table){0};
}
The compound literal creates (Table){0}
creates a temporary Table
structure object, with the initializer for the structure. Then this temporary structure object is assigned (copied to) the Table
structure object that y
points to.
It's somewhat similar to the following:
void initialize(Table *y){
Table temp_struct_object = {0}; // Normal initialization
*y = temp_struct_object; // Normal assignment (copy of object)
}
CodePudding user response:
Just memset it.
void initialize(Table *y) {
memset(y, 0, sizeof *y);
}