Question

我有一个嵌套的结构，＆＃34;内部结构＆＃34;是与成员的日期结构;日，月和年。结构包含在动态数组中。我想遍历结构并找到哪个结构具有最早的日期。我是编程新手，不太清楚如何处理这个问题。请帮忙。谢谢！

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

//define structure to store students birth date
struct date
{
    int month;
    int day;
    int year;
};
//define structure to store student info and date structure for birth date
struct studentInfo
{
    int iD;
    struct date birthDate;
    int phone;
};

int main(void)
{
    //declare and initialize variables
    int recNum = 0;     //number of records
    struct studentInfo * records = NULL;    //struct pointer, array
    //request user input  and store in recNum for record amount
    printf("\nHow many students do you need to enter records for?:");
    scanf ("%d",&recNum);
    //dynamically allocate memory
    records = (struct studentInfo*)malloc((sizeof(struct studentInfo)*recNum));
    //loop through records and request/store values from user
    int count;
    int studentNum=1;
    for(count=0;count<recNum;count++)
    {
        printf("Please enter the following for student number %d\n",studentNum);
        //request and store student ID
        printf("Student ID#:");
        scanf ("%d",&records[count].iD);
        //request and store student phone number
        printf("Student phone# (numbers only, 10 digits):");
        scanf ("%d",&records[count].phone);

        //error checking, check if phone number is 10 digits
        int phoneCount = 0;
        int phoneCopy = records[count].phone;
        while(phoneCopy != 0)
        {
            phoneCopy /= 10;
            phoneCount++;
        }
        if (phoneCount != 10)
        {
            printf("The number you have entered is not 10 digits, please re-enter:");
            scanf ("%d",&records[count].phone);
        }

        //request and store student birthdate
        printf("Student birthday (mm/dd/yyyy):");
        scanf("%d/%d/%d",&records[count].birthDate.month,&records[count].birthDate.day,
                &records[count].birthDate.year);

        //test stuff
        printf("Student number %d has an ID of %d and a phone number of %d\n", studentNum,
                records[count].iD, records[count].phone);
        studentNum++;
    }
    return 0;
}

Answer 1

#define NUMCMP(x,y) (((x) < (y)) ? -1 : ((x) > (y)) ? 1 : 0)

int compar_student_byDate(const struct studentInfo *student1, const struct studentInfo *student2){
    struct date date1 = student1->birthDate;
    struct date date2 = student2->birthDate;
    int tmp;
    if((tmp=NUMCMP(date1.year, date2.year))==0){
        if((tmp=NUMCMP(date1.month, date2.month))==0)
            return NUMCMP(date1.day, date2.day);
        else
            return tmp;
    } else
        return tmp;
}

struct studentInfo *oldest(struct studentInfo *records, int recNum){
    struct studentInfo *old = records;
    int i;
    for(i = 1;i<recNum;++i){
        if(compar_student_byDate(old, &records[i])>0)
            old = &records[i];
    }
    return old;
}

at main

struct studentInfo *old_student = oldest(records, recNum);

Answer 2

好的，首先我应该告诉你，这是一个可以有许多正确答案的问题。您可以代替创建结构数组studentInfo，创建树，每当您将新节点插入树中时，将根节点保留为许多其他解决方案中最早的节点。无论如何，对于你的简单案例，一个简单的解决方案可以如下

步骤0.您想找到

studentInfo *oldest = records;

步骤1.遍历数组

studentInfo *traveler;
for(traveler = records; i<recNum; i++, traveler++)

步骤2.比较最老的和旅行者的日期。

if(oldest->birthDate.year > traveler->birthDate.year && 
   oldest->birthDate.month > traveler->birthDate.month &&
   oldest->birthDate.day > traveler->birthDate.day)

步骤3.更新每次找到

时找到的最旧记录

oldest = traveler;

完成迭代后，最旧的记录应该是您要查找的记录。

C编程，我如何在日期结构数组中找到最早的日期？

2 个答案: