在一个while循环中“fgets”会以某种方式损坏内存吗？

Question

编辑：已解决！感谢@M OEHM注意到我有一个指向szLine的指针（代码没有显示在这里）。诀窍是将strcpy用于另一个char *指针。我怎么想念它...... :(

我现在已经调试了这个问题很长时间了，也在网上搜索过，没有找到任何帮助。如果有人能帮助我找出这个错误，我将非常感激：

我正在为图形构建一个数据库，其中 while循环读取命令的stdin 。命令可以是顶点之间的Add_Vertex和Add_Edge。 我注意到在while循环的迭代之间，内存以某种方式被改变。

所以我做了一个调试打印函数，它在迭代结束时和下一个函数的开头打印完全相同的东西。瞧，印刷品不同。这些是印刷品：

____________________________________________________________________
 started new iteration. current status:
        still no keys in the graph
_________ Executing: Add_Vertex v5 -2 -5
finished executing. current status before next iteration of while loop:
        key1 = v5
        first connection of v5 is (null)
____________________________________________________________________
 started new iteration. current status:
        key1 = v5
        first connection of v5 is (null)
_________ Executing: Add_Vertex v4 4 4
finished executing. current status before next iteration of while loop:
        key1 = v4
        first connection of v4 is (null)
        key2 = v5
        first connection of v5 is (null)
____________________________________________________________________
 started new iteration. current status:
        key1 = v4
        first connection of v4 is (null)
        key2 = v5
        first connection of v5 is (null)
_________ Executing: Add_Edge v4 v5
finished executing. current status before next iteration of while loop:
        key1 = v4
        first connection of v4 is v5
        key2 = v5
        first connection of v5 is v4
____________________________________________________________________
 started new iteration. current status:
        key1 = v4
        first connection of v4 is 3 0 5

        key2 = v5
        first connection of v5 is x v3 0 5

_________ Executing: Add_Vertex v3 0 5
finished executing. current status before next iteration of while loop:
        key1 = v3
        first connection of v3 is (null)
        key2 = v4
        first connection of v4 is 3
        key3 = v5
        first connection of v5 is x

注意最后一次迭代的打印方式与之前的不同。

这是源代码：

#define MAX_LINE_SIZE 256
int main()
{
    char szLine[MAX_LINE_SIZE];
    char* delimiters = " \t\n";
    char* pszCommand;
    // ...
    PGRAPH pg;

    pg = GraphCreate();

    while (fgets(szLine, MAX_LINE_SIZE, stdin))
    {
printf("________________________________________________________\n     started new iteration. current status:\n");
debugprints(pg);
printf("_________ Executing: %s", szLine);
    pszCommand = strtok(szLine, delimiters);

    if (NULL == pszCommand )
    {
        continue;
    }

    if ( 0 == strcmp(pszCommand, "Add_Vertex") )
    {
        // Add Vertex To graph ...
    }
    else if ( 0 == strcmp(pszCommand, "Add_Edge") )
    {
        // Add The Desired Edge ...
    }
printf("finished executing. current status before next iteration of while loop:\n");
debugprints(pg);
}

GraphDestroy(pg);
return 0;

}

这是debugprints的代码（它只打印图表的信息）：

void debugprints(PGRAPH gr) {
    char* key1 = (char*)ListGetFirstKey(gr->pl);
    char* key2 = (char*)ListGetNextKey(gr->pl,key1);
    char* key3 = (char*)ListGetNextKey(gr->pl,key2);
    PLIST adj_list1 = NULL;
    PLIST adj_list2 = NULL;
    PLIST adj_list3 = NULL;
    if (key1) {
        printf("\tkey1 = %s\n",key1);
        adj_list1 = (PLIST)(((PADJ_LIST)ListGetData(gr->pl,key1))->pEdges);
        if (adj_list1) printf("\tfirst connection of %s is %s\n",key1,(char*)ListGetFirstKey(adj_list1));
        if (key2) {
            printf("\tkey2 = %s\n",key2);
            adj_list2 = (PLIST)(((PADJ_LIST)ListGetData(gr->pl,key2))->pEdges);
            if (adj_list2) printf("\tfirst connection of %s is %s\n",key2,(char*)ListGetFirstKey(adj_list2));
            if (key3) {
                printf("\tkey3 = %s\n",key3);
                adj_list3 = (PLIST)(((PADJ_LIST)ListGetData(gr->pl,key3))->pEdges);
                if (adj_list3) printf("\tfirst connection of %s is %s\n",key3,(char*)ListGetFirstKey(adj_list3));
            }
        }
    } else printf("\tstill no keys in the graph\n");
}

谢谢!!!