c语言实现二叉树及前中后序遍历(采用递归遍历方式)

#include

#include

#include

//定义二叉树节点

typedef struct BTNode{

char data;

struct BTNode *rchild,*lchild;

}BTNode,*BTtree;

BTtree createBTNode(BTtree ptr, char value, char child){

//创建子节点

BTtree ptemp = (BTtree)malloc(sizeof(BTNode));

if(NULL == ptemp){

puts("创建子节点失败!");

exit(1);

}

ptemp->data = value;

ptemp->rchild = NULL;

ptemp->lchild = NULL;

if(child == 'R'){

ptr->rchild = ptemp;

}else if(child == 'L'){

ptr->lchild = ptemp;

}

return ptemp;

}

BTtree initBTree(){

//首先创建根节点

BTtree root = (BTtree)malloc(sizeof(BTNode));

if(root == NULL){

puts("根节点创建失败");

exit(1);

}

root->data = 'A';

root->rchild = NULL;

root->lchild = NULL;

BTtree pb = createBTNode(root,'B','L');

BTtree pc = createBTNode(root,'C','R');

BTtree pd = createBTNode(pb,'D','L');

BTtree pe = createBTNode(pb,'E','R');

BTtree pf = createBTNode(pc,'F','L');

BTtree pg = createBTNode(pc,'G','R');

return root;

}

//对二叉树进行先序遍历

void preorder(BTtree p){

if(p != NULL){

printf("%c ",p->data);

preorder(p->lchild); //先序遍历左子树

preorder(p->rchild);//先序遍历右子树

}

}

void inorder(BTtree p){

if(p != NULL){

inorder(p->lchild);

printf("%c ",p->data);

inorder(p->rchild);

}

}

void postorder(BTtree p){

if(p != NULL){

postorder(p->lchild);

postorder(p->rchild);

printf("%c ",p->data);

}

}

int main(){

BTtree btroot = initBTree();

//printf("%c\n",btroot->data);

printf("先序遍历:\n");

preorder(btroot);

printf("\n中序遍历:\n");

inorder(btroot);

printf("\n后序遍历:\n");

postorder(btroot);

return 0;

}