c - 添加动态变量时 C 列表的堆栈溢出

Question

我在学校项目中遇到一些问题。

我需要做的非常简单，我只需向列表中添加一些数据即可。 我通常知道如何做到这一点，但内存分配是动态的这一事实让我感到困惑。

这是列表:

typedef struct cList {
char *concept; // the concept learned
char *sentence; // the sentence associated with the concept
int timesUsed; //no of times the concept was used to an answer
char learnedFrom[5]; //learned either from "file" or "kbrd"
struct cList *next;
} conceptList;

以及将新数据添加到列表的函数:

void insert(char *concept, char *sentence, int timesUsed, char learnedFrom[5]) 
{
    int flag = 0, temp; 

    struct cList *link = (struct cList*) malloc(sizeof(struct cList));

    if(link!=NULL)
    {
        strcpy(link->concept,concept); //this is where the stack overflow happens first.
        strcpy(link->sentence,sentence);
        link->timesUsed = timesUsed;
        strcpy(link->learnedFrom,learnedFrom);

        link->next = head;
        head = link;

        temp = rand()%5;
        if(temp==0)
            printf("3B$ It sure is great to know everything about %s.\n", concept);
        else if(temp==1)
            printf("3B$ This information about %s is quite interesting.", concept);
        else if(temp==2)
            printf("3B$ I have to admit, learning about %s is much more interesting than it seems.", concept);
        else if(temp==3)
            printf("3B$ Learning about %s wasn't even a challenge.", concept);
        else if(temp==4)
            printf("3B$ Wow, learning about %s was so exciting!", concept);
    }
    else
        printf("3B$ Memory not available!!!\n");
}

Answer 1

第一次malloc之后，concept成员具有未初始化值。

之前需要为传递的字符串分配空间

strcpy(link->concept,concept);

所以你需要

link->concept = malloc(strlen(concept)+1);
if (link->concept != NULL)
{
    strcpy(link->concept,concept);
}
else
{
    free(link)
    return;
}

对于sentence成员来说也是如此。