源码例如以下：

这里的Key 不当为keyword对待。 而是把Item.c作为keyword对待

#include <stdlib.h>
#include <stdio.h>
//#define Key int
typedef int Key;
struct Item{
	Key key;
	char c;
};
typedef struct STnode* link;
struct STnode{
	Item item ; link l,r; int N;
};

static link head , z ;
static struct Item NULLitem ;

Key key(Item item){
	return item.key;
}
//创建一个节点 
link NEW(Item item, link l,link r, int N){
	link x = (link)malloc(sizeof *x);
	x->item = item;x->l = l;x->r = r;x->N = N;
	if(head==z)head=x; //这句话不能少！！！ 
	return x;
}
//初始化 
void STinit(){
	head = ( z = NEW(NULLitem,0,0,0));
}
//节点个数 
int STcount(){
	return head->N; 
} 
//搜索子程序 
Item searchR(link h, char v){
	char  t = h->item.c;
	if(h==z)return NULLitem;
	if(v==t) return h->item;
	if(v<t) return searchR(h->l,v);
	else return searchR(h->r,v);
}
//搜索主程序 
Item STsearch(Key v){
	return searchR(head,v);
}

//选择第K小关键值的项 K从0開始
Item selectR(link h, int k) {
	int t;
	if(h==z)return NULLitem;
	t = (h->l==z)?0:h->l->N;
	if(t>k) return selectR(h->l,k);
	if(t<k) return selectR(h->r,k-t-1);
	return h->item;
}

Item STselect(int k){
	return selectR(head,k);
}



//----------------根插入--------------------// 
//右旋转 顺时针旋转 
link rotR(link h){
	link x = h->l; h->l = x->r; x->r=h;
} 
//左旋转 逆时针旋转 
link rotL(link h){
	link x = h->r; h->r = x->l; x->l=h;
}

//插入子程序 
link insertT(link h, Item item){
//	Key v = key(item), t = key(h->item);
	char v = item.c, t = h->item.c;
	if(h==z)return NEW(item,z,z,1);
	if(v<t) {h->l = insertT(h->l,item); h = rotR(h); }
	else {h->r = insertT(h->r,item); h = rotL(h);}
	(h->N)++;return h;
}
//BST根插入主程序 
void STinsert(Item item){  //新插入的节点都会当作根节点 
	head =  insertT(head,item);
}

//----------------根插入--------------------// 

//----------------删除一个节点----方法1-----乾坤大挪移-----------// 

link partR(link h, int k) {
	int t = h->l->N;  //为什么没有推断非空？ 
	if(t>k){h->l = partR(h->l,k);h=rotR(h);} 
	if(t<k){h->r = partR(h->r,k-t-1);h=rotL(h);} 
	return h;
}
link joinLR(link a ,link b){
	if(b==z)return a;
	b=partR(b,0);
	b->l = a;
	return b;
}

link delR(link h, char k){
	link x; char t = h->item.c;
	
	if(h==z)return z;
	if(t>k)h->l=delR(h->l,k);
	if(t<k)h->r=delR(h->r,k);
	if(t==k){
		x = h;h=joinLR(h->l,h->r);free(x);
	}
	return h;
}
//删除主程序 
void STdelete(char v){
	 head = delR(head,v);
}
//----------------删除一个节点-----方法1-----乾坤大挪移----------// 



//----------------删除一个节点-----方法2---------------// 
//删除子程序 
Item deleteR(link F){
	Item tmp; link p;
	if(F->l==NULL){
		p = F;
		tmp = F->item;
		F = F->r;
		free(p);
		return tmp;
	}else return deleteR(F->l);
}
//删除子程序 
void deleteRR(link h , Key v){
	
	if(h!=NULL){
		Key t = key(h->item);
		if(v<t) deleteRR(h->l,v);
		else if(v>t) deleteRR(h->r,v);
		else
			if(h->l==NULL) { //处理仅仅有一颗子树或没有子树的情况  1 
				link p = h->r; h=p; free(p);
			}
			else if(h->r==NULL){ //处理仅仅有一颗子树或没有子树的情况  2 
				link p = h->l; h=p; free(p);
			} 
			else h->item= deleteR(h->r); //假设待删除的节点既有左子树又有右子树
										//则用该节点右子树的最左下节点替换之，维持二叉搜索树 
	}
} 
//删除主程序 
void STdelete2(Key v){
	 deleteRR(head,v);
}
//----------------删除一个节点-----方法2---------------// 

void sortR(link h){
	if(h==z)return;
	sortR(h->l);
	if(h->item.key!=0)
		printf("%c ",h->item.c);
	sortR(h->r);
}
//二叉搜索树排序 
void STsort(link h){
	sortR(h);
}
//接连两颗二叉搜索树 
link STjoin(link a ,link b){
	if(b==z)return a;
	if(a==z)return b;
	b = insertT(b,a->item);
	b->l = STjoin(a->l,b->l);
	b->r=STjoin(a->r,b->r);
	free(a);
	return b;
}

void test(){
	struct Item item1 = {322,‘a‘};
	struct Item item2 = {23,‘s‘};
	struct Item item3 = {2,‘e‘};
	struct Item item4 = {332,‘r‘};
	struct Item item5 = {332,‘c‘};
	struct Item item6 = {332,‘h‘};
	struct Item item7 = {112,‘i‘};
	STinit();
	STinsert(item1);STinsert(item2);
	STinsert(item3);STinsert(item4);
	STinsert(item5);STinsert(item6);
	STinsert(item7);
	STsort(head);
	printf("\n");
	struct Item item11 = STselect(2); 
	printf("%c\n",item11.c);
	STdelete(‘i‘);
	STsort(head);
	
	
	
}


main(){
	test();
}