[英]Memory Leak, but I can't find a way to write the code without a memory leak in C
[英]C memory leak that i can't find at all
因此,该程序一切正常,但我遇到了非常烦人的内存泄漏。 我在电脑前坐了几个小时,可以弄清楚。
我们有两个很简单的实现方式,一个结构是一个双链表,一个是存储该双链表的哈希表。
现在,我将关键字和数据插入到双向链接列表中,这里是函数。
void htable_insert(htable* ht, int key, int data) {
// TODO: Insert a new entry with the given key and data
// Overwrite the old data if the key already exists, duplicate keys are not allowed
ht_entry *new_node;
ht_entry *head;
ht_entry *it;
int sameKey;
int bucketPosition;
new_node = (ht_entry*)malloc(1*sizeof(ht_entry));
bucketPosition = key % ht->size;
sameKey = 0;
for(it = ht->entries[bucketPosition]; it != NULL; it = it->next)
{
if(it->key == key) {
it->data = data;
sameKey = 1;
free(new_node);
new_node = NULL;
break;
}
}
if(!sameKey && new_node) {
head = ht->entries[bucketPosition];
if (head == NULL) {
new_node->key = key;
new_node->data = data;
new_node->next = head;
new_node->prev = NULL;
ht->entries[bucketPosition] = new_node;
new_node = NULL;
} else {
new_node->key = key;
new_node->data = data;
new_node->next = head;
// new_node->prev = head;
head->prev = new_node;
head = new_node;
ht->entries[bucketPosition] = head;
}
}
// free(new_node);
new_node = NULL;
printf("%s\n %d", "INSERT:", key);
for(it = ht->entries[bucketPosition]; it != NULL; it = it->next){
printf("it->key: %d\nit->data: %d\n", it->key, it->data);
}
printf("%s\n", "-------------------------------");
}
这是我的valgrind消息:
==10692== Memcheck, a memory error detector
==10692== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==10692== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==10692== Command: ./chain_hash_table.out
==10692==
==10692==
==10692== HEAP SUMMARY:
==10692== in use at exit: 72 bytes in 3 blocks
==10692== total heap usage: 10 allocs, 7 frees, 376 bytes allocated
==10692==
==10692== 24 bytes in 1 blocks are definitely lost in loss record 2 of 3
==10692== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==10692== by 0x4007EE: htable_insert (htable.c:53)
==10692== by 0x400BD2: main (main.c:14)
==10692==
==10692== 48 (24 direct, 24 indirect) bytes in 1 blocks are definitely lost in loss record 3 of 3
==10692== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==10692== by 0x4007EE: htable_insert (htable.c:53)
==10692== by 0x400C25: main (main.c:18)
==10692==
==10692== LEAK SUMMARY:
==10692== definitely lost: 48 bytes in 2 blocks
==10692== indirectly lost: 24 bytes in 1 blocks
==10692== possibly lost: 0 bytes in 0 blocks
==10692== still reachable: 0 bytes in 0 blocks
==10692== suppressed: 0 bytes in 0 blocks
==10692==
==10692== For counts of detected and suppressed errors, rerun with: -v
==10692== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)
我所知道的始终是第一次插入表,这就是为什么它在第一次插入后在main(18)行上显示其余内容的原因。
谢谢你们的时间和帮助:)
检查循环中的break语句,它在第一次迭代时中断,并且不取消分配节点。
中断应放在for循环内。
如果要在C程序中分配空间,除非最后释放所有内容,否则最终将导致内存泄漏。
对于您当前的程序,我假设您最终无法正确释放。 因此,问题不在htable_insert
函数之内,而在您的释放/清除函数之内。
如果您在htable_insert
释放链表节点,那么您将无法在程序的其余部分中访问它们,并且会遇到段错误。
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