函数中的c-malloc()调用-分段错误:11

Question

我是一个C初学者，刚刚尝试实现makeRandomTree（）函数来随机创建一个二进制树。

尽管编译有时是成功的（并非总是！），但程序在运行时会以错误"Segmentation fault:11"退出。我认为错误位于makeRandomNode（）-函数中，malloc（）的动态内存分配位于该函数中。不幸的是，我还没能找到错误。

我希望有人能帮我

这是源代码：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define NUMBER_OF_NODES 10
#define RANDOM_NUMBER_MAX 99
struct node {
    int nodeValue;
    struct node *parentNode;
    struct node *leftChild;
    struct node *rightChild;
};
typedef struct node node;
node* makeRandomNode(unsigned int *randomSeed) {
    //random number in the range [0;RANDOM_NUMBER_MAX]
    int random = (rand_r(randomSeed) % (RANDOM_NUMBER_MAX + 1));
    node *newNode = (node *) malloc(sizeof(node));
    newNode->nodeValue = random;
    newNode->parentNode = NULL;
    newNode->leftChild = NULL;
    newNode->rightChild = NULL;
    return newNode;
}
void insertNode(node *root, node *newNode) {
    if (newNode->nodeValue <= root->nodeValue) {
        if (root->leftChild == NULL) {
            root->leftChild = newNode;
            newNode->parentNode = root;
        }
        else {
            insertNode(root->leftChild, newNode);
        }
    }
    else {
        if (root->rightChild == NULL) {
            root->rightChild = newNode;
            newNode->parentNode = root;
        }
        else {
            insertNode(root->rightChild, newNode);
        }
    }
}
node* makeRandomTree(int numberOfNodes) {
    int i;
    unsigned int randomSeed;
    node *root;
    node *newNode;
    randomSeed = time(NULL);
    root = makeRandomNode(&randomSeed);
    for (i = 1; i < numberOfNodes; i++) {
        newNode = makeRandomNode(&randomSeed);  
        insertNode(root, newNode);
    }
    return root;
}
int main(int argc, char *argv[]) {
    node *tree = makeRandomTree(NUMBER_OF_NODES);
    printf("A random-binary-tree with %i nodes was created successfully!!!n", NUMBER_OF_NODES);
    printf("'NodeValue' of root is %in", tree->nodeValue);
    printf("'NodeValue' of left child of root is %in", tree->leftChild->nodeValue);
    printf("'NodeValue' of right child of root is %in", tree->rightChild->nodeValue);
    printf("etc.n");
}

Answer 1

树处理代码总体上看起来不错，但这可能是一个问题：

printf("'NodeValue' of left child of root is %in", tree->leftChild->nodeValue);
printf("'NodeValue' of right child of root is %in", tree->rightChild->nodeValue);

如果树碰巧没有左子级或右子级，则尝试取消引用NULL-指针。通过if (tree->leftChild) ... 进行保护