c - 如何在C中对一组结构进行排序

Question

我创建了 4 个变量结构并为 age 分配了值。

 struct database {
 int id_number;
 int age;
 float salary;
 };

 main()
 {
 struct database employee[4];
 struct database current; // Used later in my attempted sorting

 employee[1].age = 12;

 employee[2].age = 112;

 employee[3].age = 2;

 employee[4].age = 22;

我尝试了各种方法来尝试对这些进行排序，但都失败了， 例如:

 for(i = 0; i < 4; i++)
 {
     current = employee[i];//"current" was previously assigned to the same type of struct
     j = i;

     while(employee[j-1].age > current.age)
     {
        employee[j] = employee[j-1];
        j = j-1;
     }
     employee[j] = current;
 }

Answer 1

许多错误，正如其他人在评论中指出的那样。

(数组访问越界、排序算法不正确等)

<小时/>

要对struct数组进行排序，最简单的方法是使用 qsort 您需要定义自定义比较器，如下所示:

typedef struct database db;

int sort_by_age(void *a, void *b)
{
  db *_a = (db *)a;
  db *_b = (db *)b;

  if( _a->age > _b->age  ) return -1;
  if( _a->age == _b->age ) return 0;

  return 1;
}

然后像这样使用它，

int no_of_employee = 4;

qsort( employee, no_of_employee, sizeof(db), sort_by_age );