按字典顺序对结构数组进行排序

Question

我需要根据姓氏对学生进行排序，或者如果他们的姓氏相同，则根据他们名字的字典顺序进行排序。

#include <stdio.h>
struct Student {
  char name[20], surname[20];
};
void sort(struct Student students[], int n) {
  int i, j, temp;
  for (i = 0; i < n; i++)
    for (j = i + 1; j < n; j++)
      if (students[j].surname > students[i].surname ||
          students[j].name > students[i].name) {
        temp = i;
        students[i] = students[j];
        students[j] = students[temp];
      }
}
void main() {
  struct Student students[6] = {
      {"Mujo", "Mujic"}, 
      {"Meho", "Mujic"}, 
      {"Pero", "Peric"},
      {"Beba", "Bebic"}, 
      {"Mujo", "Mujic"}, 
      {"Fata", "Fatic"},
  };
  sort(students, 6);
  int i;
  for (i = 0; i < 6; i++)
    printf("%s %s\n", students[i].surname, students[i].name);
}

这六次只打印一个学生。你能帮我解决这个问题吗？

注意：不允许使用辅助数组

Answer 1

你的交换代码是可疑的——坏了，我相信。一个大警钟是 temp 的类型——它需要是 struct Student.

您有：

    temp = i;
    students[i] = students[j];
    students[j] = students[temp];

你需要：

    struct Student temp = students[i];
    students[i] = students[j];
    students[j] = temp;

显然，也删除定义 int temp;。

但是，也有其他问题（一如既往）。您不能使用关系运算符有效地比较字符串 — 使用 strcmp()。而且您的排序测试也是错误的，即使修改为使用 strcmp().

此代码完成工作，按降序对名称进行排序：

#include <stdio.h>
#include <string.h>

struct Student
{
    char name[20];
    char surname[20];
};

static void sort(struct Student students[], int n)
{
    for (int i = 0; i < n; i++)
    {
        for (int j = i + 1; j < n; j++)
        {
            int rc = strcmp(students[j].surname, students[i].surname);
            if (rc > 0 ||
                (rc == 0 && strcmp(students[j].name, students[i].name) > 0))
            {
                struct Student temp = students[i];
                students[i] = students[j];
                students[j] = temp;
            }
        }
    }
}

static void dump_array(const char *tag, size_t size, const struct Student *students)
{
    printf("%s (%zu):\n", tag, size);
    for (size_t i = 0; i < size; i++)
        printf("%s %s\n", students[i].surname, students[i].name);
}

int main(void)
{
    struct Student students[] =
    {
        {"Mujo", "Mujic"},
        {"Meho", "Mujic"},
        {"Pero", "Peric"},
        {"Zebra", "Elephant"},
        {"Beba", "Bebic"},
        {"Mujo", "Mujic"},
        {"Abelone", "Shells"},
        {"Fata", "Fatic"},
    };
    enum { NUM_STUDENTS = sizeof(students) / sizeof(students[0]) };

    dump_array("Before", NUM_STUDENTS, students);
    sort(students, NUM_STUDENTS);
    dump_array("After", NUM_STUDENTS, students);

    return 0;
}

输出：

Before (8):
Mujic Mujo
Mujic Meho
Peric Pero
Elephant Zebra
Bebic Beba
Mujic Mujo
Shells Abelone
Fatic Fata
After (8):
Shells Abelone
Peric Pero
Mujic Mujo
Mujic Mujo
Mujic Meho
Fatic Fata
Elephant Zebra
Bebic Beba

按字典顺序对结构数组进行排序

Sort struct array in lexicographical order

c

arrays

string

struct