c++的这个语句改写为C语言怎么写

Question

struct node{
int value;
node *l, *r;
node(int value = 0, node *l = NULL, node *r = NULL):value(value), l(l), r(r){}
};

root = new node(in[flag]);

改成C语言的结构体为
typedef struct node{
int value;
struct node *l,*r;
}node;
这样子的时候，c++的这句该怎么用C语言实现?
root = new node(in[flag]);

Answer 1

root = (struct node * )malloc(sizeof(struct node) * in[flag]);