c语言编写程序从键盘输入5个学生的信息，包括学生学号、姓名、性别、出生年月及成绩，用结构体数组保存学生的信息，要求用函数实现结构体数组的输入输出及求成绩最高学生的序号。

下面是一份实现上述要求的C语言程序：

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

#define NUM_STUDENTS 5

// 定义学生结构体
struct student {
    int id;
    char name[20];
    char gender;
    int birth_year;
    float score;
};

// 函数声明
void input_students(struct student *students, int n);
void output_students(struct student *students, int n);
int find_max_score(struct student *students, int n);

int main()
{
    struct student students[NUM_STUDENTS];
    input_students(students, NUM_STUDENTS);
    output_students(students, NUM_STUDENTS);
    int max_index = find_max_score(students, NUM_STUDENTS);
    printf("The student with the highest score is %s, with a score of %.1f\n", students[max_index].name, students[max_index].score);
    return 0;
}

// 输入学生信息的函数
void input_students(struct student *students, int n)
{
    for (int i = 0; i < n; i++) {
        printf("Please input the information of student %d:\n", i+1);
        printf("ID: ");
        scanf("%d", &students[i].id);
        printf("Name: ");
        scanf("%s", students[i].name);
        printf("Gender (M/F): ");
        scanf(" %c", &students[i].gender);
        printf("Birth year: ");
        scanf("%d", &students[i].birth_year);
        printf("Score: ");
        scanf("%f", &students[i].score);
    }
}

// 输出学生信息的函数
void output_students(struct student *students, int n)
{
    printf("=====================================\n");
    printf("ID\tName\tGender\tBirth Year\tScore\n");
    printf("=====================================\n");
    for (int i = 0; i < n; i++) {
        printf("%d\t%s\t%c\t%d\t\t%.1f\n", students[i].id, students[i].name, students[i].gender, students[i].birth_year, students[i].score);
    }
    printf("=====================================\n");
}

// 求成绩最高学生序号的函数
int find_max_score(struct student *students, int n)
{
    int max_index = 0;
    float max_score = students[0].score;
    for (int i = 1; i < n; i++) {
        if (students[i].score > max_score) {
            max_score = students[i].score;
            max_index = i;
        }
    }
    return max_index;
}

这个程序使用了一个结构体数组`students`来保存学生信息。程序先调用`input_students`函数从键盘输入学生信息，并将结果保存到结构体数组中。然后调用`output_students`函数将学生信息输出到屏幕上。最后调用`find_max_score`函数求出成绩最高的学生的序号，并将结果输出到屏幕上。