为什么每次输出的只有最后一个节点的信息，前面的节点为什么输出不了呢 - 编程论坛

#2

吹水佬2020-04-08 14:38

    while(head!=NULL){
            printf("%d,%s",head->number,head->name);
            head = head->next;
    }

#3

LGD3350600872020-04-09 09:04

回复 2楼吹水佬

不行呢还是只能输出最后一个节点的信息

#4

fulltimelink2020-04-09 11:37

程序代码：

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
typedef struct player {
    int number;
    char name[20];
    struct player*next;
}Player;
Player*game(int sum);
int main()
{
    int sum;
    printf("请输入玩家个数");
    scanf("%d", &sum);
    Player*head = game(sum);
    while (head != NULL) {
        printf("%d,%s", head->number, head->name);
        head = head->next;

    }
    return 0;
}
Player*game(int sum)
{
    int i;
    Player*head = NULL, *pt, *pre = NULL;    //头节点过度节点，尾节点
    for (i = 0; i < sum; i++) {

        pt = (Player*)malloc(sizeof(Player));
        scanf("%d%s", &pt->number, pt->name);
        if (pt != NULL) {
            if (i == 0) {
                head = pt;
                pre = pt;
            }
            else {
                pre->next = pt;
                pre = pt;
            }


        }
        pt->next = NULL;
    }
    return head;
}

#5

fulltimelink2020-04-09 11:44

以下是引用fulltimelink在2020-4-9 11:37:08的发言：

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
typedef struct player {
    int number;
    char name[20];
    struct player*next;
}Player;
Player*game(int sum);
int main()
{
    int sum;
    printf("请输入玩家个数");
    scanf("%d", &sum);
    Player*head = game(sum);
    while (head != NULL) {
        printf("%d,%s", head->number, head->name);
        head = head->next;

    }
    return 0;
}
Player*game(int sum)
{
    int i;
    Player*head = NULL, *pt, *pre = NULL;    //头节点过度节点，尾节点
    for (i = 0; i < sum; i++) {

        pt = (Player*)malloc(sizeof(Player));
        scanf("%d%s", &pt->number, pt->name);
        if (pt != NULL) {
            if (i == 0) {
                head = pt;
                pre = pt;
            }
            else {
                pre->next = pt;
                pre = pt;
            }


        }
        pt->next = NULL;
    }
    return head;
}

不能编辑了，输出完还需要free

程序代码：

while (head != NULL) {
        printf("%d,%s", head->number, head->name);
        head = head->next;

    }
    free(head);
    return 0;

#6

LGD3350600872020-04-10 11:01

以下是引用fulltimelink在2020-4-9 11:37:08的发言：

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
typedef struct player {
    int number;
    char name[20];
    struct player*next;
}Player;
Player*game(int sum);
int main()
{
    int sum;
    printf("请输入玩家个数");
    scanf("%d", &sum);
    Player*head = game(sum);
    while (head != NULL) {
        printf("%d,%s", head->number, head->name);
        head = head->next;

    }
    return 0;
}
Player*game(int sum)
{
    int i;
    Player*head = NULL, *pt, *pre = NULL;    //头节点过度节点，尾节点
    for (i = 0; i < sum; i++) {

        pt = (Player*)malloc(sizeof(Player));
        scanf("%d%s", &pt->number, pt->name);
        if (pt != NULL) {
            if (i == 0) {
                head = pt;
                pre = pt;
            }
            else {
                pre->next = pt;
                pre = pt;
            }


        }
        pt->next = NULL;
    }
    return head;
}

  if (i == 0) {
                head = pt;
                pre = pt;
            }
问题1：为什么不可以把if(i==0)改为if(head!=NULL)呢？？？？因为刚开始game函数里head就是空的，进入第二次循环时它就是非空了
问题2：我在game函数里给pt动态申请了内存空间我应该在哪里给它返回内存空间呢？

#7

fulltimelink2020-04-10 11:18

回复 6楼 LGD335060087

head != null也可以的，都是用来判断第一次而已，如果你愿意，也可以把首次malloc放到for外面，这样循环里面就不用每次都if了，这个看你自己的想法！
第二个问题，没明白你想说啥？

#8

吹水佬2020-04-10 11:36

以下是引用LGD335060087在2020-4-9 09:04:39的发言：

不行呢还是只能输出最后一个节点的信息

我只看了输出，输入也有问题，看代码应该是头插入。

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

typedef struct player
{
    int number;
    char name[20];
    struct player *next;
} Player;

Player* game(int sum);

int main()
{
    int sum;
    printf("请输入玩家个数");
    scanf("%d",&sum);
    Player* head;
    head=game(sum);
    int i;
    for (; head; head=head->next)
        printf("%d,%s\n",head->number,head->name);
    return 0;
}

Player* game(int sum)
{
    int i;
    Player *head=NULL,*pt;
    for(i=0; i<sum; i++)
    {
        pt=(Player*)malloc(sizeof(Player));
        if(pt!=NULL)
        {
            scanf("%d%s",&pt->number,pt->name);
            pt->next = head;
            head = pt;
        }
    }
    return head;
}

#9

LGD3350600872020-04-10 13:29

以下是引用fulltimelink在2020-4-10 11:18:30的发言：

第二个问题，没明白你想说啥？

问题2：给pt malloc应该在哪里free(pt)。申请内存空间不还需要返还内存空间吗

#10

fulltimelink2020-04-10 13:35

回复 9楼 LGD335060087

整体确认不使用了就可以一起free掉 ,可以封装成一个函数

程序代码：

void freeList(struct node* head)
{
   struct node* tmp;

   while (head != NULL)
    {
       tmp = head;
       head = head->next;
       free(tmp);
    }

}

[此贴子已经被作者于2020-4-10 13:45编辑过]