所以我正在尝试用 C++ 编写一个基本的红黑树。这是我第一次从 C 到 C++ 的真正过渡，我遇到了范围问题。我正在尝试使用全局变量来跟踪树的根，因为我很懒，不想让每个函数都传回旧的或新的根。无论如何，我在任何函数或类之外声明了指针（名为 root），在我看来，任何人都应该可以看到它。当我编译时，我得到：
main.cpp: In member function ‘void node::ins(int)’:
main.cpp:23:4: error: ‘root’ was not declared in this scope
main.cpp: In member function ‘void node::case3()’:
main.cpp:110:4: error: ‘root’ was not declared in this scope
因此，类中的函数看不到全局变量，但主函数可以。我该怎么做才能让类中的函数看到这个变量？提前致谢。最大限度
#include <iostream>
#include <cstdio>
using namespace std;
const int BLACK = 0;
const int RED = 1;
class node{
public:
node *parent = NULL;
node *left = NULL;
node *right = NULL;
int color = RED;
int num = -1;
int isRoot(void){
if(parent == NULL) return 1;
else return 0;
};
void ins(int newNum){
if(isRoot() && num == -1){//if first insertion
num = newNum;
color = BLACK;
root = this;
}else if(newNum < num)
if(left == NULL){
left = new node;
left->parent = this;
left->num = newNum;
left->fixColor();
}else
left->ins(newNum);
else
if(right == NULL){
right = new node;
right->parent = this;
right->num = newNum;
right->fixColor();
}else
right->ins(newNum);
};
int uncleColor(void){
if(parent != NULL){
if(parent->parent != NULL){
node *grandparent = parent->parent;
if(grandparent->left == parent)
if(grandparent->right == NULL)
return BLACK;
else
return grandparent->right->color;
else{
if(grandparent->left == NULL)
return BLACK;
else
return grandparent->left->color;
}
}else
cout << "[Error] Grandparent DNE, at root\n";
}else
cout << "[Error] Parent DNE, at root\n";
return -1;
};
void fixColor(void){
if(isRoot()){
color = BLACK;
}else if(color == RED){
if(parent->color == RED){//if parent is black, nothing violated
int uncle = uncleColor();
if(uncle == RED){//uncle is red too
case1();
parent->parent->fixColor();//call recursivly on grandparent
}else if(uncle == BLACK){//uncle is black
case2();//case 2 will then call case 3
}else
cout << "[Error] fixColor uncle color mismatch\n";
}
}else
cout << "[Error] fixcolor node is black?\n";
};
void case1(void){
node *grandparent = parent->parent;
node *uncle = NULL;
if(grandparent->left == parent)
uncle = grandparent->right;
else
uncle = grandparent->left;
uncle->color = BLACK;
parent->color = BLACK;
grandparent->color = RED;
};
void case2(void){
node *grandparent = parent->parent;
if(this == parent->right && parent == grandparent->left){
rotate_left();
left->case3();
}else if(this == parent->left && parent == grandparent->right){
rotate_right();
right->case3();
}else
case3();
};
void case3(void){
node *grandparent = parent->parent;
parent->color = BLACK;
color = RED;
if(this == parent->left)
grandparent->rotate_right();
else
grandparent->rotate_left();
if(parent->isRoot())
root = parent;
};
void rotate_left(void){
node *grandparent = parent->parent;
grandparent->left = this;
parent->right = this->left;
this->left = parent;
parent->parent = this;
parent = grandparent;
};
void rotate_right(void){
node *grandparent = parent->parent;
grandparent->right = this;
parent->left = this->right;
this->right = parent;
parent->parent = this;
parent = grandparent;
};
void del(int val){
};
};
node *root = NULL;
int main(int argc, char **argv){
root = new node;
char READ_task;
int READ_val;
FILE *txtPtr = NULL;
if((txtPtr = fopen(argv[1],"r")) == NULL){printf("[Error] Unable to Load File: '%s'\nExiting...\n",argv[1]);}
else{
while(fscanf(txtPtr, "%c%d", &READ_task, &READ_val) == 2){
if(READ_task == 'i')
root->ins(READ_val);
else if(READ_task == 'd')
root->del(READ_val);
else
cout << "Instruction from file not i or d\n";
}
}
return 0;
}