構造体とアルゴリズムとポインタが

Question

iは、構造体とポインタを使用して簡単なfriend-リストを作ったが、私はそのが正しいことを印刷しない「コードでいくつかの問題を抱えている

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; 
} 

とイムは、友達リストを印刷しようとしたとき：

どうすれば解決できますか？ 、何が `（F + I）で開始する

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; 
}