c - 访问NULL指针

这是我的代码的一部分...而且我遇到了几个主要问题...
好的，到目前为止，我能看到的大多数问题都已解决。
当我结束程序时，这是错误消息：S

 HEAP SUMMARY:
==15468==     in use at exit: 20 bytes in 1 blocks
==15468==   total heap usage: 1 allocs, 0 frees, 20 bytes allocated
==15468==
==15468== 20 bytes in 1 blocks are definitely lost in loss record 1 of 1
==15468==    at 0x4025BD3: malloc (vg_replace_malloc.c:236)
==15468==    by 0x8048601: newnode (myassignment.c:27)
==15468==    by 0x804885E: insertavl (myassignment.c:88)
==15468==    by 0x8048B33: main (myassignment.c:156)
==15468==
==15468== LEAK SUMMARY:
==15468==    definitely lost: 20 bytes in 1 blocks
==15468==    indirectly lost: 0 bytes in 0 blocks
==15468==      possibly lost: 0 bytes in 0 blocks
==15468==    still reachable: 0 bytes in 0 blocks
==15468==         suppressed: 0 bytes in 0 blocks
==15468==
==15468== For counts of detected and suppressed errors, rerun with: -v
==15468== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 13 from 8)
typedef struct node *tree;

struct node {
   int data;
   char name;
   int height;
   struct node *left;
   struct node *right;
};




static tree newnode(int d,char n){
   tree t = malloc(sizeof(struct node));
   t->data = d;
   t->name=n;
   t->left = NULL;
   t->right = NULL;
   memoize(t);
   return t;
}

static tree modnode(int d, char n,tree t){
   if (d > t->data){
       t->data=d;
       t->name=n;
       t->right = t->right;}
   else{
       t->data=t->data;
       t->name=t->name;
       t->right = t->right;}
  return t;
}



tree insertavl(tree t, int d,const char *n){
   if (t == NULL) return newnode(d,*n);
   else if (t->name==*n) return modnode(d,*n,t->right);// <=========(1)
   else {
      printf("went right");
      setright(t, insertavl(t->right, d,n));
   }
   return t;
}


int main(void) {
  int i = 0;
  char foo[11];
  int c;
  tree t= NULL;
  for(c=0;c<=1000;c++) {
    i = readstring(foo,10);
    if(i == 0) break;
    if (strcmp("score",foo)==0){
   int a=0;
   int point;
   char n[21];
   printf ("Enter name \n");
   a=readstring (n,20);
   printf ("Enter score \n");
   scanf("%d", &point);
   t=insertavl(t,point,n);}
   if (strcmp("highscore",foo)==0){
       printf ("%d \n", highsc(t));}

   if (t==NULL){
      printf ("false");}
    }
   return 0;
 }

我知道我的程序效率不高，但我想先修复错误。，我们将不胜感激！

最佳答案

那么检查malloc的返回值呢？

关于c - 访问NULL指针，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/11645371/