strlen 和 malloc：C 内存泄漏

这个问题是无效的！我没有正确地释放学生！我会尽快接受向我透露这一点的答案！

我是 C 新手，正在练习 malloc。从宏观上讲，我正在编写一个链表库；这个 create_student 函数是我将用来测试我的链表库的许多函数之一。问题是...我运行 valgrind 并调用此函数，它表明第一个 malloc 导致了多个内存泄漏。据我所知，这一切看起来都很可靠：

typedef struct Student
{
        char* first_name; /* This will be malloc'd!*/
    char* last_name; /* This will also be malloc'd */
    int grade;
    long id;
} Student;


Student* create_student(const char* first_name, const char* last_name, int grade, long gtid)
{

        /* First allocate a student on the heap */
        Student *newStudentp = (malloc(sizeof(Student)));


    /* Allocate enough space for the first and last names */
    newStudentp -> last_name = (malloc(strlen(last_name)));
    newStudentp -> first_name = (malloc(strlen(first_name)));



        // AND copy the first and last name to the first and last name fields in the struct   
    strncpy(newStudentp -> first_name, first_name, strlen(first_name));
    strncpy(newStudentp -> last_name, last_name, strlen(last_name));



        /* Set the grade and id */
    newStudentp -> grade = grade;
    newStudentp -> id = id;

        */ 
    return newStudentp;
}

我来自 valgrind 的错误消息（有几个）如下所示：

==4285==    9 bytes in 1 blocks are definitely lost in loss record 8 of 8
==4285==    at 0x4025BD3: malloc (vg_replace_malloc.c:236)
==4285==    by 0x804855B: create_student (test.c:24)
==4285==    by 0x8048748: main (test.c:109)

第 24 行是

newStudentp -> last_name = (malloc(strlen(last_name))); 

line.

我是否对 strlen 有一些根本性的误用导致了错误？

这里有几个问题：

    newStudentp -> last_name = (malloc(strlen(last_name)));
    newStudentp -> first_name = (malloc(strlen(first_name)));

strlen只给出长度直到但不包括终止'\0'。但它也必须被存储，所以你应该使用strlen(last_name) + 1在这两种情况下。

另外，你的strncpy()最好使用分配的缓冲区的大小而不是源字符串的大小来完成，这样您就可以避免写入超出数组的高边界。但既然你已经用过malloc(strlen(...) + 1)，你可以简单地使用strcpy() here.