c - 第二次重新分配后 VS 发疯

Question

所以我有一个输入文件，其中包含以下文本(每行=用户):

012345678;danny;cohen;22;M;danny1993;123;1,2,4,8;Nice person
223325222;or;dan;25;M;ordan10;1234;3,5,6,7;Singer and dancer
349950234;nadav;cohen;50;M;nd50;nadav;3,6,7,8;Engineer very smart

首先，代码为一个用户分配空间，然后为另外 1 个用户(每个用户)重新分配空间。问题是，一切都很顺利，直到第二次重新分配，然后它向我显示错误“Exercise 6.exe 已触发断点”。我还要提到一开始的错误:““wntdll.pdb未加载”，但我尝试执行VS建议的操作-使用符号进行操作。然后出现“触发断点”错误。

我尝试切换文本文件中的行，但没关系，第二次尝试重新分配后出现问题。

让我向您展示代码的相关部分:

int main()
{
    //intiallizing variables
    int menArraySize = 0;
    //creating a NULL array pointer (array) for men
    User *head = NULL;
    readInputFile(head, &menArraySize, list);
}

void readInputFile(User *head, int *menArraySize, WomenList *list)
{
    //temporary data types for the the stracture we're creating
    char id[10];
    char *firstName = NULL;
    char *lastName = NULL;
    char age[4] = { 0 };
    char gender = '\0';
    char *userName = NULL;
    char *password = NULL;
    char hobbies = 0;
    char *description = NULL;
    //regular function data types
    int i = 0, j = 0, k = 0, currentDetail = 1, size;
    char currentString[212] = { 0 };
    int currentChar;

    //opening the input file
    FILE *input = fopen("input.txt", "r");
...
//long code for allocating room for each string (firstName, lastName, etc...)- irelevant
...
    head = addMale(head, menArraySize, id, firstName, lastName, age,
        gender, userName, password, hobbies, description);
...
//rest of the function isn't relevant
}

User* addMale(User *head ,int *menArraySize, char id[], char *firstName, 
char *lastName,char age[], char gender, char *userName,


char *password, char hobbies, char *description)
            {
                //if the array is empty, allocate room for one user
                if (*menArraySize == 0)
                {
                    head = (User *)malloc(1 * sizeof(User));
                }
                //if the array isn't empty, reallocate room for one more user
                else
                {
                    **this is the line in which the error occurs (second time reallocating,
                   third dynamic allocation total for this pointer)**
                head = (User *)realloc(head, (*menArraySize + 1) * sizeof(User));
                }
                //if the allocation failed
                if (head == NULL)
                    exit(1);
                //pointing to the new user we created
                head = &head[*menArraySize];
                //apply all details to the user
                strcpy(head->id, id);
                head->firstName = firstName;
                head->lastName = lastName;
                strcpy(head->age, age);
                head->gender = gender;
                head->userName = userName;
                head->password = password;
                head->hobbies = hobbies;
                head->description = description;
                //applying an index number to the user
                head->index = *menArraySize;
                //pointing back to the head of the array
                head = &head[0];
                //updating the variable showing the size of the array
                *menArraySize = *menArraySize + 1;
                return head;
            }

为什么会发生这种情况？我能做什么来修复它？谢谢!

Answer 1

这里:

head = &head[*menArraySize];

您指向新位置，但您也覆盖(并丢失)head原始值(除非您减去)。当你这样做时:

head = &head[0];

您认为您正在恢复原始值，但这没有任何效果。您只需引用/取消引用相同的值即可。

解决方案:使用另一个User *temp 值来引用新位置。使用realloc后保持head不变。