用C++语言写一段代码，实现简单的学籍管理功能，要求能够录入学生信息，输出学生信息，根据输入时间与课程选课，统计每门课的学分绩点，统计每学期的平均绩点，统计重修科目。注意：要用C++语言写。

好的，我可以为你提供一份简单的学籍管理功能代码，具体实现如下所示：

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

struct student {
    char name[20];
    char id[10];
    int age;
    float scores[5];
    float credit[5];
    float total_credits;
    float total_gpa;
    int repeat[5];
    int semester;
};

void input(struct student s[], int n);
void output(struct student s[], int n);
void choose(struct student s[], int n);
void calculate(struct student s[], int n);
void display(struct student s[], int n);

int main() {
    int n;
    printf("请输入学生人数：");
    scanf("%d", &n);
    struct student s[n];
    input(s, n);
    output(s, n);
    choose(s, n);
    calculate(s, n);
    display(s, n);
    return 0;
}

void input(struct student s[], int n) {
    printf("请输入学生信息，包括姓名、学号、年龄、成绩：\n");
    for(int i=0; i<n; i++) {
        scanf("%s %s %d %f %f %f %f %f", s[i].name, s[i].id, &s[i].age, &s[i].scores[0], &s[i].credits[0], &s[i].scores[1], &s[i].credits[1], &s[i].scores[2], &s[i].credits[2], &s[i].scores[3], &s[i].credits[3], &s[i].scores[4], &s[i].credits[4]);
        s[i].total_credits = 0;
        s[i].total_gpa = 0;
        for(int j=0; j<5; j++) {
            s[i].repeat[j] = 0;
            s[i].total_credits += s[i].credits[j];
        }
    }
}

void output(struct student s[], int n) {
    printf("学生信息如下：\n");
    for(int i=0; i<n; i++) {
        printf("%s %s %d %.2f %.2f %.2f %.2f %.2f\n", s[i].name, s[i].id, s[i].age, s[i].scores[0], s[i].credits[0], s[i].scores[1], s[i].credits[1], s[i].scores[2], s[i].credits[2], s[i].scores[3], s[i].credits[3], s[i].scores[4], s[i].credits[4]);
    }
}

void choose(struct student s[], int n) {
    printf("请输入要选课的学期和科目编号：\n");
    int semester, subject;
    scanf("%d %d", &semester, &subject);
    for(int i=0; i<n; i++) {
        if(s[i].semester == semester) {
            if(s[i].scores[subject-1] == -1) {
                printf("该课程已选！\n");
            } else {
                printf("请输入成绩：");
                scanf("%f", &s[i].scores[subject-1]);
                s[i].credits[subject-1] *= s[i].scores[subject-1] / 10.0 - 5;
            }
        }
    }
}

void calculate(struct student s[], int n) {
    for(int i=0; i<n; i++) {
        float total_score = 0;
        int total_repeat = 0;
        for(int j=0; j<5; j++) {
            if(s[i].scores[j] == -1) {
                s[i].repeat[total_repeat++] = j;
            } else {
                total_score += s[i].scores[j] * s[i].credits[j];
            }
        }
        s[i].total_gpa = total_score / s[i].total_credits;
    }
}

void display(struct student s[], int n) {
    printf("每门课的学分绩点如下：\n");
    for(int i=0; i<5; i++) {
        float total_score = 0;
        float total_credits = 0;
        for(int j=0; j<n; j++) {
            if(s[j].scores[i] != -1) {
                total_score += s[j].scores[i] * s[j].credits[i];
                total_credits += s[j].credits[i];
            }
        }
        printf("第%d门课学分绩点为：%.2f\n", i+1, total_score / total_credits);
    }
    printf("每学期的平均绩点如下：\n");
    float total_gpa = 0;
    int total_students = 0;
    for(int i=1; i<=5; i++) {
        float semester_gpa = 0;
        int semester_students = 0;
        for(int j=0; j<n; j++) {
            if(s[j].semester == i) {
                semester_gpa += s[j].total_gpa;
                semester_students++;
            }
        }
        if(semester_students > 0) {
            total_gpa += semester_gpa / semester_students;
            total_students++;
            printf("第%d学期的平均绩点为：%.2f\n", i, semester_gpa / semester_students);
        }
    }
    printf("总平均绩点为：%.2f\n", total_gpa / total_students);
    printf("重修科目如下：\n");
    for(int i=0; i<n; i++) {
        if(s[i].total_gpa < 2.0) {
            printf("学生%s 重修科目：", s[i].name);
            for(int j=0; j<5; j++) {
                if(s[i].repeat[j] != 0) {
                    printf("%d ", j+1);
                }
            }
            printf("\n");
        }
    }
}

这份代码主要实现了学籍管理功能，包括录入学生信息、输出学生信息、根据输入时间与课程选课、统计每门课的学分绩点、统计每学期的平均绩点、统计重修科目等功能。希望能对你有所帮助！