结构体问题 建立通讯录

通讯录排序：建立一个通讯录，输入n(n<10)个朋友的信息，包括姓名、生日、电话号码，生日包括三项：年、月、日。按照年龄从大到小的顺序依次输出通讯录。
请问我该怎么改啊

#include<stdio.h>
struct birth
{
    int year,month,day;
};

struct friendlist
{
    char name[20];
    struct birth birthday;
    char tel[11];
};
void input(struct friendlist f[],int n)
{
    for(int i=0;i<n;i++)
    {
        scanf("%s",&f[i].name);
        scanf("%d %d %d",&f[i].birthday.year,&f[i].birthday.month,&f[i].birthday.day);
        scanf("%s",&f[i].tel); 
    }
}
void output(struct friendlist f[],int n)
{
    for(int i=0;i<n;i++)
    {
        printf("%s",f[i].name);
        printf("%d年%d月%日",f[i].birthday.year,f[i].birthday.month,f[i].birthday.day);
        printf("%s",f[i].tel);
        printf("\n");
    }
}
void sort(struct friendlist f[],int n)
{
    for(int i=0;i<n-1;i++)
    {
        int t;
        if(f[i].birthday.year*365+f[i].birthday.month*30+f[i].birthday.day>f[i+1].birthday.year*365+f[i+1].birthday.month*30+f[i+1].birthday.day)
        {
            t=f[i];
            f[i]=f[i+1];
            f[i+1]=t;
        }
}
int main(void)
{
    struct friendlist friends[10];
    int n;
    
    scanf("%d",&n);
    
    input(friends,n);
    sort(friends,n);
    output(friends,n);
    
    return 0; 
}

你这问题挺多的， 把完整代码 发出来【别发图片】，

#include<stdio.h>
struct birth
{
    int year,month,day;
};

struct friendlist
{
    char name[20];
    struct birth birthday;
    char tel[11];
};

void input(struct friendlist f[],int n)
{
    for(int i=0;i<n;i++)
    {
        scanf("%s",&f[i].name);
        scanf("%d %d %d",&f[i].birthday.year,&f[i].birthday.month,&f[i].birthday.day);
        scanf("%s",&f[i].tel); 
    }
}

void output(struct friendlist f[],int n)
{
    for(int i=0;i<n;i++)
    {
        printf("%s ",f[i].name); // 加个空格，好展示
        // 日少了 d， 日后面加个空格，好展示
        printf("%d年%d月%d日 ",f[i].birthday.year,f[i].birthday.month,f[i].birthday.day);
        printf("%s",f[i].tel);
        printf("\n");
    }
}

void sort(struct friendlist f[],int n)
{
    for(int i=0;i<n-1;i++)
    {
        struct friendlist t; // t 是结构体，不是int
        if(f[i].birthday.year*365+f[i].birthday.month*30+f[i].birthday.day>f[i+1].birthday.year*365+f[i+1].birthday.month*30+f[i+1].birthday.day)
        {
            t=f[i];
            f[i]=f[i+1];
            f[i+1]=t;
        }
    } // 少了一个 }
}



int main(void)
{
    struct friendlist friends[10];
    int n;
    
    scanf("%d",&n);

    // 如果要换行 
    // getchar(); 接收一下换行符
    
    input(friends,n);
    sort(friends,n);
    output(friends,n);
    
    return 0; 
}