我基本上只需要另一双眼睛;我知道我错过了一些小东西，但目前我找不到它。
这是我的二进制树程序的全部内容。
#include <stdio.h>
#include <stdlib.h>
//-------------------------Structure definition----------------------------------------------------------------------------------
struct tree {
int data;
struct tree *left;
struct tree *right;
};
//-------------------------Function definitions--------------------------------------------------------------------------------
int traverse(struct tree *); //Traverse to print the data.
struct tree * insert(struct tree *, int num); //insert data.
int search(struct tree *, int num); //Find a number, return found/not found status.
struct tree * delete(struct tree *, int num); //Delete a number.
int maxdepth(struct tree *); //Find depth of tree.
int bal(struct tree *); //Indicates whether or not the tree is balanced.
void help(); //Simple help routine.
//-------------------------Help function to display commands. ----------------------------------------------------------
void help()
{
printf("\n Q to quit program. \n");
printf(" # to insert # into the list. \n");
printf(" s # to search for # in the list. \n");
printf(" d # to delete # from list. \n");
printf(" p to print the entire list. \n");
printf(" ? to view this message again. \n\n");
}
//-------------------------Insert function to sort and insert user input. ----------------------------------------------
struct tree * insert(struct tree *root, int num)
{
if(root==NULL)
{
root=malloc(sizeof(struct tree));
root->data = num;
root->left = root->right=NULL;
return(root);
}
if(num > root->data)
{
root->right=insert(root->right, num);
return(root);
}
if(num < root->data)
{
root->left=insert(root->left, num);
return(root);
}
/* if(num==root->data)
{
return (root);
}
*/
}
//-------------------------Search function. Just returns a 1/0 for yes/no. ------------------------------------------
int search(struct tree *root, int num)
{
if(root==NULL)return(0);
if(num==root->data)return(1);
if(1==search(root->left, num) || 1==search(root->right, num))
{
return(1);
}
else
{
return(0);
}
}
//-------------------------Delete function. Deletes target, replaces with following num. ----------------------------
struct tree * delete(struct tree *root, int num)
{
struct tree *parent;
struct tree *successor; //Placeholders.
//If root isn't there...
if(root=NULL)
{
printf("Number not found. \n\n");
return NULL;
}
//If target is greater than root->data, go right.
if(num>root->data)
{
root->right=delete(root->right, num);
return (root);
}
//If target is less than root->data, go left.
if(num<root->data)
{
root->left=delete(root->left, num);
return(root);
}
//If target equals root->data, put on headphones. Push play.
if(num==root->data) //DELETE SEGFAULTS HERE (FROM GDB)
{
if((root->left==NULL) && (root->right==NULL)) //If no children....
{
free(root);
return NULL;
}
if((root->left==NULL) && (root->right!=NULL)) //If right child...
{
successor=root->right;
free(root);
return(successor);
}
if((root->left!=NULL) && (root->right==NULL)) //If left child...
{
successor=root->left;
free(root);
return(successor);
}
if((root->left!=NULL) && (root->right!=NULL)) //If root has two children
{
parent=root; //Remember root node
successor=root->right; //Find his replacement
if(successor->left==NULL) //If no left child, replace with successor and free root.
{
successor->left=root->left;
free(root);
return(successor);
}
else
{
while(successor->left!=NULL) //If there is a left child, follow to the end.
{
successor=successor->left;
}
parent->data=successor->data; //Replace root with successor, free root.
free(parent);
return(successor);
}
}
}
}
/*-------------------------Balance function. Indicates whether or not the tree is balanced. ------------------------------------------------------
int bal(struct tree *root)
{
int ld; //Depth of left branches.
int rd; //Depth of right branches.
if(root=NULL)
{
return(1);
}
ld=maxdepth(root->left); //Segfaults here. BLAH.
rd=maxdepth(root->right);
if((ld-rd>1) || (rd-ld>1))
{
return(0);
}
}
*/
//------------------------MaxDepth function to calculate the depth of the tree. --------------------------------
int maxdepth(struct tree *root)
{
int ldepth;
int rdepth;
if(root==NULL)
{
return 0;
}
ldepth=maxdepth(root->left);
rdepth=maxdepth(root->right);
if(ldepth > rdepth)
{
return ldepth+1;
}
else
{
return rdepth+1;
}
}
//-------------------------Traverse (print) --------------------------------------------------------------------------------------
int traverse(struct tree *root)
{
if(root==NULL)
{
return 0;
}
traverse(root->left);
printf("%d ", root->data);
traverse(root->right);
}
//-------------------------Main! ------------------------------------------------------------------------------------
int main(void)
{
struct tree *root=NULL;
char buffer[120]; //Temp storage
int num; //User input will move from buffer to here.
int searchVal;
int balval;
//Memory Allocations block.
root=NULL;
printf("Hello. \n");
while(1==1)
{
printf("> ");
fgets(buffer, sizeof(buffer), stdin);
switch(buffer[0])
{
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
if(1==(sscanf(buffer, "%d", &num))){
if(0==search(root, num))
{
root=insert(root, num);
}
else printf("Number is already in list. \n");
}
break;
case 's':
if(1==(sscanf(buffer, "s %d", &num))){
if(1==search(root, num)){
printf("That number is in the list. \n");
}else{
printf("That number is not in the list. \n");
}
}
break;
case 'p':
traverse(root);
printf("\n Tree depth: %d \n", maxdepth(root));
//if(0==bal(root)){
// printf("Balance returned 0, your tree sucks. \n");
//}
//if(1==bal(root))
//{
// printf("Balance returned 1, congratulations. Go listen to Sunlounger. :) \n");
//}
break;
case 'd':
if(1==(sscanf(buffer, "d %d", &num))){
root=delete(root, num);
}
case '?':
help();
break;
case 'q':
case 'Q':
exit(0);
break;
default:
help();
break;
}
}
}
在删除范围内，if（num＆gt; root-＆gt; data）是否发生了段错误（第105行）。这是该函数第一次尝试从tree * root访问某些内容。正如您可以从代码中看出的那样，平衡函数中也存在段错误，但我现在并不担心它。
任何帮助或指示（哈哈）都表示赞赏。提前谢谢。
答案 0 :(得分：3)
首先看下面的错误。这应该可以解决您的问题。享受..
在函数struct tree * delete(struct tree *root, int num)
这不是检查null ..而是将根分配给null。后来在该函数中，您试图取消引用null指针（Seg fault）
if(root=NULL)
应该是
if(root==NULL) or if(!root)