代码

#define _CRT_SECURE_NO_WARNINGS#include <stdio.h>
#include <string.h>
#include <stdlib.h>
void Save();struct SUser
{int nNumb;char sName[20];float fMath;
}g_user[100];void Print()
{puts("\n学号\t姓名\t数学");int i = 0;while (g_user[i].nNumb){if(g_user[i].nNumb>0)printf("%d\t%s\t%0.1f\n", g_user[i].nNumb, g_user[i].sName, g_user[i].fMath);++i;}printf("\n\t总共有%d条学生信息\n\n", i);system("pause");
}int Check(int nNumb)
{int i = 0;while (g_user[i].nNumb){if (nNumb == g_user[i].nNumb)return 1;++i;}return 0;
}void Add()
{int nNumb;printf("请输入学号：");scanf_s("%d", &nNumb);while (Check(nNumb)){printf("该学号已存在，请重新输入(0取消输入)：");scanf_s("%d", &nNumb);if (nNumb == 0)return;}int i = 0;while (g_user[i].nNumb>0)++i;//scanf("%d%s%f",&g_user[i].nNumb,)g_user[i].nNumb = nNumb;printf("请输入姓名：");scanf_s("%s", g_user[i].sName,sizeof(g_user[i].sName));printf("请输入成绩：");scanf_s("%f", &g_user[i].fMath);Save();Print();
}void Delete()
{printf("请输入要删除的学号：");int nNumb;scanf_s("%d", &nNumb);int i = 0;//int flag = 0;while (g_user[i].nNumb){if (g_user[i].nNumb == nNumb){//flag = 1;g_user[i].nNumb = -1;break;}++i;}//if (flag == 0)if (g_user[i].nNumb!=-1)//if (g_user[i].nNumb==0)puts("你输入的学号不存在！");else{Save();Print();}
}void Modify()
{printf("请输入要修改的学号：");int nNumb;scanf_s("%d", &nNumb);int i = 0;while (g_user[i].nNumb){if (g_user[i].nNumb == nNumb){printf("%d\t%s\t%0.1f\n", g_user[i].nNumb, g_user[i].sName, g_user[i].fMath);printf("请输入新的姓名：");scanf_s("%s", g_user[i].sName, sizeof(g_user[i].sName));printf("请输入新的成绩：");scanf_s("%f", &g_user[i].fMath);return;}++i;}Save();Print();
}void Load()
{FILE* pf = fopen("data.lv", "r");if (!pf)return;int i = 0;while (fread(&g_user[i], 1, sizeof(SUser), pf) == sizeof(SUser))++i;fclose(pf);
}void Save()
{FILE* pf = fopen("data.lv", "w");if (!pf){puts("保存数据时失败！");return;}int i = 0;while (g_user[i].nNumb){if (-1 != g_user[i].nNumb)fwrite(&g_user[i], 1, sizeof(SUser), pf);++i;}fclose(pf);
}int Judge(int nIndex,int j)
{if (nIndex == 1)return g_user[j].nNumb > g_user[j + 1].nNumb;if (nIndex == 2)return strcmp(g_user[j].sName, g_user[j + 1].sName) > 0;if (nIndex == 3)return g_user[j].fMath < g_user[j + 1].fMath;return 0;
}//int Judge(int nIndex,SUser* p) // p是指向第j个结构体的地址
//3种基本排序：冒泡 插入 选择
//分治法排序：归并排序 快速排序
void Sort(int nIndex) // 选择排序
{int i = 0;while (g_user[i+1].nNumb){int nMin = i;int j = i + 1;while (g_user[j].nNumb){if (g_user[j].nNumb < g_user[nMin].nNumb)nMin = j;++j;}if (nMin != i){SUser t = g_user[i];g_user[i] = g_user[nMin];g_user[nMin] = t;}++i;}
}int DispMenu()
{system("cls");puts("1.按学号排序");puts("2.按姓名排序");puts("3.按成绩排序");puts("0.返回主菜单");printf("请选择：");int i = 0;scanf_s("%d", &i);switch (i){case 0:break;case 1:case 2:case 3:Sort(i);Print();break;}return i;
}void SetColor()
{printf("请输入背景色：");char s[20] = "color ";fflush(stdin);s[6] = getchar();printf("请输入前景色：");fflush(stdin);s[7] = getchar();system(s);
}int Menu()
{int i = 0;system("cls");puts("1.浏览所有信息");puts("2.添加信息");puts("3.删除信息");puts("4.修改信息");puts("5.查找信息");puts("6.颜色设置");puts("0.退出");printf("请选择：");scanf_s("%d", &i);switch (i){case 0:break;case 1:while (DispMenu());break;case 2:Add();break;case 3:Delete();break;case 4:Modify();break;case 6:SetColor();break;}return i;
}int main()
{system("color 3f");Load();while (Menu());return 0;
}

运行结果