c - 具有结构体和指针的算法

Question

我使用结构和指针制作了一个简单的 friend 列表，但我的代码有一些问题'它没有打印正确的内容

    typedef struct friends {
    int namesize;
    char* myfriends;
}friends;

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int main(void)
{
    int numfriends = 0;
    int*p_friends = &numfriends;
    int i = 0, count = 0;
    printf("Welcome , here is a list of your friends \n");
    printf("plesase enter the number of your friends \n");
    scanf("%d", &numfriends); //gets the number of the friends
    printf("you have %d friends \n", numfriends);

    friends *f= malloc(sizeof(friends) * numfriends); // malloc
    printf("now please enter thier'S name \n");
    for (i = 0; i < numfriends; i++)
    {
        count++; // for looking at the number of the friend
        (f+i)->myfriends= (char*)malloc(sizeof(char) * numfriends); // malloc
        printf("enter the name of friend NO.%d ", count);
        fgets((f + i)->myfriends,20,stdin); // entering the names of the friends
        (f +i)-> namesize = strlen((f + i)->myfriends) + 1;
        ((f + i)->myfriends) = (char*)realloc((f + i)->myfriends, sizeof(char) * numfriends * (f + i)->namesize); //realloc

    }
    for (int j = 0; j < numfriends; j++)
    {
        printf("The name of friend NO %d is: %s \n", j + 1, ((f + j)->myfriends)); //printing the names
        free((f + j)->myfriends);
    }



    system("pause");
    return 0;
}

当我尝试打印 friend 列表时:

我该如何解决这个问题？

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct friends {
    int namesize;
    char* myfriends;
}friends;

#define MAX_NAME_SIZE 20

int main(void){
    int numfriends = 0;
    //int*p_friends = &numfriends;//unused
    int i = 0, count = 0;
    printf("Welcome , here is a list of your friends \n");
    printf("plesase enter the number of your friends \n");
    scanf("%d%*c", &numfriends); //%*c eat newline
    printf("you have %d friends \n", numfriends);

    friends *f= malloc(sizeof(friends) * numfriends);
    printf("now please enter thier'S name \n");
    for (i = 0; i < numfriends; i++){
        count++; // for looking at the number of the friend
        f[i].myfriends = (char*)malloc(sizeof(char) * (MAX_NAME_SIZE + 1));//f[i]. short than (f+i)->
        printf("enter the name of friend NO.%d ", count);
        fgets(f[i].myfriends, MAX_NAME_SIZE + 1, stdin); // entering the names of the friends
        f[i].myfriends[strcspn(f[i].myfriends, "\n")] = '\0'; //remove newline
        f[i].namesize = strlen(f[i].myfriends) + 1;
        f[i].myfriends = realloc(f[i].myfriends, f[i].namesize);//Cast is not necessary in C. alos sizeof(char) is always 1 in C.
    }
    for (int j = 0; j < numfriends; j++){
        printf("The name of friend NO %d is: %s \n", j + 1, f[j].myfriends); //printing the names
        free(f[j].myfriends);
    }
    free(f);

    system("pause");
    return 0;
}