写在前面

第一次用C语言编写系统，经验不足，还有很多不完善之处还请见谅。

编程实现

#include <stdio.h>
#include <stdlib.h>
#include <string.h>#define MAXSIZE 100     //课程最多人数
#define COURSENUM 6     //课程门数typedef struct student {int num;                    //学号char name[20];              //姓名float score[COURSENUM];     //各门课的成绩float ave;                  //平均分
} StuType;typedef struct Students {StuType *elem;              //学生数组空间起始地址int length;                 //学生实际个数
} Students;void create(Students *sa, int n) {int i, j;char temp;float ave = 0, sum = 0;for (i = 0; i < n; i++) {printf("请输入第%d个学生的信息：\n", i+1);printf("学号：");scanf("%d%c", &sa->elem[i].num, &temp);//为了姓名读入正确，需要去掉录入学号信息时输入的回车printf("姓名：");gets(sa->elem[i].name);printf("六门课的成绩：英语、哲学、高等数学、数据结构、操作系统、计算机网络：");for (j = 0; j < COURSENUM; j++) {scanf("%f", &sa->elem[i].score[j]);sum+=sa->elem[i].score[j];}sa->elem[i].ave = sum/COURSENUM;sa->length = n;sum = 0;}
}void display(Students sa) {int i, j;printf("%d个学生的信息如下：\n", sa.length);printf("学号、姓名、英语、哲学、高等数学、数据结构、操作系统、计算机网络、平均分\n");for (i = 0; i < sa.length; i++) {printf("%d  %s", sa.elem[i].num, sa.elem[i].name);for (j = 0; j < COURSENUM; j++) {printf("%8.1f", sa.elem[i].score[j]);}printf("%8.1f\n", sa.elem[i].ave);}
}void searchByNum(Students sa, int num) {int i, j;for (i = 0; i < sa.length; i++) {if (sa.elem[i].num == num) {printf("学号、姓名、英语、哲学、高等数学、数据结构、操作系统、计算机网络、平均分\n");printf("%d  %s", sa.elem[i].num, sa.elem[i].name);for (j = 0; j < COURSENUM; j++) {printf("%8.1f", sa.elem[i].score[j]);}printf("%8.1f\n", sa.elem[i].ave);break;}}if (i == sa.length){printf("查无此人！\n");}
}void searchByName(Students sa, char *name) {int i, j, flag = 0;for (i = 0; i < sa.length; i++) {if (strcmp(sa.elem[i].name, name) == 0) {printf("学号、姓名、英语、哲学、高等数学、数据结构、操作系统、计算机网络、平均分\n");printf("%d  %s", sa.elem[i].num, sa.elem[i].name);for (j = 0; j < COURSENUM; j++) {printf("%8.1f", sa.elem[i].score[j]);}printf("%8.1f\n", sa.elem[i].ave);flag = 1;break;}}if (!flag) {printf("查无此人！\n");}
}void add(Students *sa) {int i;float sum = 0;char temp;printf("请输入该学生的信息：\n");printf("学号：");scanf("%d%c", &sa->elem[sa->length].num, &temp);//为了姓名读入正确，需要去掉录入学号信息时输入的回车printf("姓名：");gets(sa->elem[sa->length].name);printf("六门课的成绩：英语、哲学、高等数学、数据结构、操作系统、计算机网络：");for (i = 0; i < COURSENUM; i++) {scanf("%f", &sa->elem[sa->length].score[i]);sum+=sa->elem[sa->length].score[i];}sa->elem[sa->length].ave = sum/COURSENUM;sa->length++;
}void deleteByName(Students *sa, int num) {int i, j, flag = 0;for (i = 0; i < sa->length; i++) {if (sa->elem[i].num == num) {for (j = i; j < sa->length; j++) {sa->elem[j] = sa->elem[j+1];}sa->length--;flag = 1;break;}}if (!flag) {printf("查无此人！\n");}
}void modifyByName(Students *sa, int num) {int selected;int i, flag = 0;char temp;for (int i = 0; i < sa->length; i++) {if (sa->elem[i].num == num) {for (;;) {printf("------请选择要修改的项目：------\n");printf("        1:姓名\n");printf("        2:英语成绩\n");printf("        3:哲学成绩\n");printf("        4:高等数学成绩\n");printf("        5:数据结构成绩\n");printf("        6:操作系统成绩\n");printf("        7:计算机网络成绩\n");printf("        8:返回主菜单\n");scanf("%d", &selected);scanf("%c", &temp);switch (selected) {case 1:printf("请输姓名：");gets(sa->elem[i].name);break;case 2:printf("请输入英语成绩：");scanf("%f", &sa->elem[i].score[0]);average(sa);break;case 3:printf("请输入哲学成绩：");scanf("%f", &sa->elem[i].score[1]);average(sa);break;case 4:printf("请输入高等数学成绩：");scanf("%f", &sa->elem[i].score[2]);average(sa);break;case 5:printf("请输入数据结构成绩：");scanf("%f", &sa->elem[i].score[3]);average(sa);break;case 6:printf("请输入操作系统成绩：");scanf("%f", &sa->elem[i].score[4]);average(sa);break;case 7:printf("请输入计算机网络成绩：");scanf("%f", &sa->elem[i].score[5]);average(sa);break;case 8:return;}}flag = 1;break;}}if (!flag) {printf("查无此人！\n");}
}void average(Students *sa) {int i, j;float ave = 0, sum = 0;for (j = 0; j < COURSENUM; j++) {scanf("%f", &sa->elem[i].score[j]);sum+=sa->elem[i].score[j];}sa->elem[sa->length].ave = sum/COURSENUM;
}void sortByCourse(Students *sa) {int selected;for (;;) {printf("------请选择排序依据的科目：------\n");printf("        1:英语\n");printf("        2:哲学\n");printf("        3:高等数学\n");printf("        4:数据结构\n");printf("        5:操作系统\n");printf("        6:计算机网络\n");printf("        7:返回主菜单\n");scanf("%d", &selected);switch (selected) {case 1:sortByCourse2(sa, 0);break;case 2:sortByCourse2(sa, 1);break;case 3:sortByCourse2(sa, 2);break;case 4:sortByCourse2(sa, 3);break;case 5:sortByCourse2(sa, 4);break;case 6:sortByCourse2(sa, 5);break;case 7:return;}}
}void sortByCourse2(Students *sa, int course) {int i, j, max;StuType stu;for (i = 0; i < sa->length; i++) {max = i;for (j = i+1; j < sa->length; i++) {if (sa->elem[j].score[course] > sa->elem[max].score[course]) {max = j;}}if (max != i) {stu.num = sa->elem[i].num;strcpy(stu.name, sa->elem[i].name);for (j = 0; j < COURSENUM; j++) {stu.score[j] = sa->elem[i].score[j];}sa->elem[i].num = sa->elem[max].num;strcpy(sa->elem[i].name, sa->elem[max].name);for (j = 0; j < COURSENUM; j++) {sa->elem[i].score[j] = sa->elem[max].score[j];}sa->elem[max].num = stu.num;strcpy(sa->elem[max].name, stu.name);for (j = 0; j < COURSENUM; j++) {sa->elem[max].score[j] = stu.score[j];}}}
}void level(Students sa) {int selected;for (;;) {printf("------请选择统计分数段的科目：------\n");printf("        1:英语\n");printf("        2:哲学\n");printf("        3:高等数学\n");printf("        4:数据结构\n");printf("        5:操作系统\n");printf("        6:计算机网络\n");printf("        7:返回主菜单\n");scanf("%d", &selected);switch (selected) {case 1:levelByCourse(sa, 0);break;case 2:levelByCourse(sa, 1);break;case 3:levelByCourse(sa, 2);break;case 4:levelByCourse(sa, 3);break;case 5:levelByCourse(sa, 4);break;case 6:levelByCourse(sa, 5);break;case 7:return;}}
}void levelByCourse(Students sa, int course) {int num[6] = {0}, i, j;for (int i = 0; i < sa.length; i++) {if (sa.elem[i].score[course] < 60) {num[0]++;} else if (sa.elem[i].score[course] < 70) {num[1]++;} else if (sa.elem[i].score[course] < 80) {num[2]++;} else if (sa.elem[i].score[course] < 90) {num[3]++;} else {num[4]++;}}switch (course) {case 0:printf("英语成绩分数段分布人数：60分以下、60~69分、70~79分、80~89分、90分以上分别为：\n");break;case 1:printf("哲学成绩分数段分布人数：60分以下、60~69分、70~79分、80~89分、90分以上分别为：\n");break;case 2:printf("高等数学成绩分数段分布人数：60分以下、60~69分、70~79分、80~89分、90分以上分别为：\n");break;case 3:printf("数据结构成绩分数段分布人数：60分以下、60~69分、70~79分、80~89分、90分以上分别为：\n");break;case 4:printf("操作系统成绩分数段分布人数：60分以下、60~69分、70~79分、80~89分、90分以上分别为：\n");break;case 5:printf("计算机网络成绩分数段分布人数：60分以下、60~69分、70~79分、80~89分、90分以上分别为：\n");break;}for (int i = 0; i < 5; i++) {printf("%6d", num[i]);}printf("\n");
}int main() {int selected = 10, count, num;Students sa;char name[20], temp;sa.elem = (StuType *)malloc(sizeof(StuType)*MAXSIZE);for (;;) {printf("------本程序为学生程序管理系统，请选择系统功能：------\n");printf("        1:录入全部学生信息\n");printf("        2:按学号查询学生信息\n");printf("        3:按姓名查询学生信息\n");printf("        4:添加一个学生信息\n");printf("        5:按学号删除学生信息\n");printf("        6:按学号修改学生信息\n");printf("        7:显示所有学生信息\n");printf("        8:按课程成绩从高到低显示所有学生信息\n");printf("        9:按分数段统计学生信息\n");printf("        0:退出程序\n");scanf("%d", &selected);switch (selected) {case 1:printf("请输入学生个数：");scanf("%d", &count);create(&sa, count);break;case 2:printf("请输入要查询的学生的学号：");scanf("%d", &num);searchByNum(sa, num);break;case 3://将菜单选择时键入的回车符删掉scanf("%c", &temp);printf("请输入要查询的学生的姓名：");gets(name);searchByName(sa, name);break;case 4:add(&sa);break;case 5:printf("请输入要删除的学生的学号：");scanf("%d", &num);deleteByName(&sa, num);break;case 6:printf("请输入要修改信息的学生的学号：");scanf("%d", &num);modifyByName(&sa, num);break;case 7:display(sa);break;case 8:sortByCourse(&sa);break;case 9:level(sa);break;case 0:return 0;}}return 0;
}