刷力扣时常犯的错:
runtime error: member access within misaligned address 0xbebebebebebebebe for type ‘struct TreeNode’, which requires 8 byte alignment [TreeNode.c]
0xbebebebebebebebe: note: pointer points here
原因:
我们在访问某个变量时,因为这个变量中含有未赋值的指针。定义但是不赋值的指针叫做野指针。野指针指向不明,对程序有不可知的后果,引用了更是出大问题,所以,c语言严格反对野指针。
在这个题目中,使用
TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
申请了一块内存空间给root结点,然而并没有对root->left和root->right指针赋初值也没有置为NULL。导致后面给left和right赋值时报错。
若加上两条语句,则可解决:
TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
root->left = NULL; // 问题在这里!!没有赋值的空指针一定要设为NULL
root->right = NULL; //
这是一段正确的代码:
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
typedef struct TreeNode TreeNode;
TreeNode* CreatTree(int* preorder,int* inorder,int l1,int r1,int l2,int r2){
if(l1 > r1 || l2 > r2){ // 说明此时无孩子,返回NULL
printf("%d",1);
return NULL;
}
TreeNode* root = (TreeNode*)malloc(sizeof(TreeNode));
root->left = NULL; // 问题在这里!!没有赋值的空指针一定要设为NULL
root->right = NULL; //
int i;
root->val = preorder[l1];
for(i=l2;inorder[i]!=root->val;i++);
int lLen = i - l2;
int rLen = r2 - i;
if(lLen > 0){
root->left = CreatTree(preorder,inorder,l1+1,l1+lLen,l2,l2+lLen-1);
}
if(rLen > 0){
root->right = CreatTree(preorder,inorder,r1-rLen+1,r1,r2-rLen+1,r2);
}
return root;
}
struct TreeNode* buildTree(int* preorder, int preorderSize, int* inorder, int inorderSize){
TreeNode* root = CreatTree(preorder,inorder,0,preorderSize-1,0,inorderSize-1);
return root;
}
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leetcode常见错误:runtime error: member access within misaligned address 0xbebebebebe
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