頭指針隨鏈接列表項而變化

Question

該程序應該打印新元素和開始元素。 但是每次我分配一個新元素時，開始元素都會發生變化。 init_class()返回指向類的指針。

/*
  Class->Albert
            |
            V
         Einstein

*/


#include "datadef.h"
int main(int argc, char* argv[])
{
    char Name[30][30];

    if (argc != 2)
    {
        printf("Incorrect number of arguments, please retry...\n");
        exit(0);
    }

    Class* classp;
    classp = init_class();

    FILE* fp;
    fp = fopen(argv[1],"r");

    if (fp == NULL)
    {
        printf("File pointer allocation error...Ending the program..\n");
        exit(0);
    }
    int count = 0;
    Student* prevp;
    Student* currp;
    while(!feof(fp))
   {
        fscanf(fp,"%s",Name[count]);
        currp = init(Name[count]);
        if (!count)
        {
            classp->startp = currp;
            printf("Assigned the head pointer\n");
        }
        else
        {
            prevp->nextp = currp;
            printf("appending to the pre-existing list\n");
        }
        count+=1;
        prevp = currp;
        printf("Current : %s \n",currp->name);
        printf("Head : %s \n",classp->startp->name);
        printf("\n\n");
    }

結果：

指定頭指針

當前：阿爾伯特

負責人：阿爾伯特

追加到先前存在的列表

當前：愛因斯坦

負責人：愛因斯坦

預期結果：

指定頭指針

當前：阿爾伯特

負責人：阿爾伯特

追加到先前存在的列表

當前：愛因斯坦

負責人：阿爾伯特

這是init（）

/*init()*/
Student* init(char* name)
{
    Student* currentp = (Student*)malloc(sizeof(Student));
    if (!currentp)
    {
        printf("pointer allocation problem..Ending the program...\n");
        exit(0);
    }
    currentp->name = name;
    currentp->nextp = NULL;
    currentp->scoreHeadp = NULL;

   return currentp;

}

Answer 1

您使用的是相同的char Name[30]; 為每個學生。

Answer 2

編輯您的初始化函數：

/*init()*/
Student* init(char* name)
{
    Student* currentp = (Student*)malloc(sizeof(Student));
    /* Allocate memory also for the student name */
    currentp->name = (char *)malloc(strlen(name) * sizeof(char));
    if (!currentp)
    {
        printf("pointer allocation problem..Ending the program...\n");
        exit(0);
    }
    //currentp->name = name;
    strncpy(currentp->name, name, strlen(name));
    currentp->nextp = NULL;
    currentp->scoreHeadp = NULL;

   return currentp;
}