```c++ TreeNode* BuildTree(char c[],int s,int e){ //当s==e时，数组只剩一个元素，而且必是操作数值 if(s==e){ TreeNode *node = new TreeNode; node->rChild = node->lChild = NULL; node->val = c[s]; return node; } //从后向前找+- 从后开始遍历纯粹是为了好看 for(int i=e;i>=s;i--){ if(c[i]=='+'||c[i]=='-'){ //这个+-做根节点 TreeNode *node = new TreeNode; node->lChild = node->rChild = NULL;//左右子置空 node->val = c[i];//将操作符赋值给该节点 node->lChild = BuildTree(c,s,i-1);//分开的左子树，s到i-1是+-号左边的那部分 node->rChild = BuildTree(c,i+1,e); //分开的右子树，i+1到e是+-号右边的内容 return node;//返回到上一级给左右子，或者给根 } } for(int j=s;j<=e;j++){ if(c[j]=='*'){ //没有+-后运算符*作根 TreeNode *node = new TreeNode; node->lChild = node->rChild = NULL; node->val = c[j]; node->lChild = BuildTree(c,s,j-1); node->rChild = BuildTree(c,j+1,e); return node; } } for(int j=e;j>=s;j--){ if(c[j]=='/'){ //没有+-后运算符/作根 //因为优先级问题从后面读起 TreeNode *node = new TreeNode; node->lChild = node->rChild = NULL; node->val = c[j]; node->lChild = BuildTree(c,s,j-1); node->rChild = BuildTree(c,j+1,e); return node; } } }将这段代码更改为 c 语言

把代码中的 TreeNode* 替换为 struct TreeNode*，同时需要加上头文件和结构体定义，代码如下：

#include <stdio.h>
#include <stdlib.h>

struct TreeNode {
    char val;
    struct TreeNode* lChild;
    struct TreeNode* rChild;
};

struct TreeNode* BuildTree(char c[], int s, int e) {
    //当s==e时，数组只剩一个元素，而且必是操作数值
    if (s == e) {
        struct TreeNode* node = (struct TreeNode*)malloc(sizeof(struct TreeNode));
        node->rChild = node->lChild = NULL;
        node->val = c[s];
        return node;
    }
    //从后向前找+- 从后开始遍历纯粹是为了好看
    for (int i = e; i >= s; i--) {
        if (c[i] == '+' || c[i] == '-') {
            //这个+-做根节点
            struct TreeNode* node = (struct TreeNode*)malloc(sizeof(struct TreeNode));
            node->lChild = node->rChild = NULL;  //左右子置空
            node->val = c[i];  //将操作符赋值给该节点
            node->lChild = BuildTree(c, s, i - 1);  //分开的左子树，s到i-1是+-号左边的那部分
            node->rChild = BuildTree(c, i + 1, e);  //分开的右子树，i+1到e是+-号右边的内容
            return node;  //返回到上一级给左右子，或者给根
        }
    }
    for (int j = s; j <= e; j++) {
        if (c[j] == '*') {
            //没有+-后运算符*作根
            struct TreeNode* node = (struct TreeNode*)malloc(sizeof(struct TreeNode));
            node->lChild = node->rChild = NULL;
            node->val = c[j];
            node->lChild = BuildTree(c, s, j - 1);
            node->rChild = BuildTree(c, j + 1, e);
            return node;
        }
    }
    for (int j = e; j >= s; j--) {
        if (c[j] == '/') {
            //没有+-后运算符/作根
            //因为优先级问题从后面读起
            struct TreeNode* node = (struct TreeNode*)malloc(sizeof(struct TreeNode));
            node->lChild = node->rChild = NULL;
            node->val = c[j];
            node->lChild = BuildTree(c, s, j - 1);
            node->rChild = BuildTree(c, j + 1, e);
            return node;
        }
    }
}