Question

此代码应该生成由用户输入的十个名称的链接列表它应该打印出该列表。

#include<stdio.h>
#include<stdlib.h>
struct NameList
{
    char *name;
    struct NameList *nname;
};
typedef struct NameList NL;

int main()
{
    int i;
    NL *first;
    NL *next;
    first = (NL*)malloc(sizeof(NL));
    if (first ==NULL)
            printf("Memory not properly allocated\n");
    NL *pNames;
    pNames =  first;
    for(i = 0; i<10; i++)
    {
            printf("Enter a name: ");
            scanf("%s", &pNames->name);
            if(i == 9)
                    next = NULL;
            else
                    next = (NL*)malloc(sizeof(NL));
            pNames->nname = next;
            pNames = pNames->nname;
    }

到此为止没有问题，我输入了十个名字，但一进入我得到一个分段错误的姓氏。我猜这是源于此，但我完全不确定

        pNames = first;
        while(pNames != NULL)
        {
                printf("%s\n", pNames->name);
                pNames = pNames->nname;
        }


    }

Answer 1

这一行是来源：

printf("Enter a name: ");
scanf("%s", &pNames->name);

最好像这样创建一个静态缓冲区：

char buf[20];

然后

printf("Enter a name: ");
scanf("%s", buf);

最后：

pNames->name = strdup(buf);

编辑：为了完整起见，存在缓冲区溢出的风险。其中超过某些字符超过缓冲区的末尾会导致不确定的行为。这可以通过 @ebyrob 的建议以这种方式缓解

fgets(buf, 20, stdin);

Answer 2

allocate space for "name", preferably use std::string

    you need to get "next" node.

      for(i = 0; i<10; i++)
            {
                    printf("Enter a name: ");
                    scanf("%s", &pNames->name);
                    if(i == 9)
                            next = NULL;
                    else
                            next = (NL*)malloc(sizeof(NL));
                    pNames->nname = next;
                    pNames = next;
            }

              pNames = first;
                while(pNames != NULL)
                {
                        printf("%s\n", pNames->name);
                        pNames = pNames->next;
                }

Answer 3

您尚未分配内存来保存NameList个对象的name字段。 char *字段的类型为scanf(%s, &pNames->name);，它有足够的空间用于指针，而不是字符串。当您执行scanf时，您告诉scanf将名称写入该内存位置，但这将覆盖比存储指针所需的字节多得多的内容。

相反，您可以先将malloc加载到临时数组中，然后char *tempbuff = malloc(128); // or some large enough buffer for (i = 0; i<10; ++i) { // load the input into tempbuff first scanf("%s", tempbuff); // now make room for the string in the current object pNames->name = malloc(strlen(tempbuff)+1); // leave room for trailing null // now copy it from the tempbuff to its new home strcpy(pNames->name,tempbuff); .... // rest of code加载足够的空间来保存它

@numbers = @client.available_phone_numbers.get('US').local.list(
   near_lat_long: '40.6928,-73.9903',
   distance: '5'
)

链表 - 分段错误

3 个答案: