modnum.c

本程序根据高校的学生情况

/* modnum.c ：修改学生信息        */
#include "stdio.h"
void ModifyByNumber()
 {
    int i,j,k;
    long modnum;    /*存储教师输入的要修改的学生学号*/
    /*输入各项修改后信息*/
    long Number;
    char Name[20];
    float chinesescore;
    float mathscore;
    float heji;
    student TmpS;   /*定义进行操作时的临时结构体变量*/
    student s[SIZE];/*SIZE，在shead.h头文件中定义的常量，值为100  */
    int recNumber;
    char DataFile[40] = "",next;
    /*DataFile存储学生信息的文件名，next为是否进行下一次删除操作的选项*/
    FILE *fp;/*====fp指针指向存储数据的文件名====*/
    /*提示教师输入要进行修改记录的文件名*/
    printf("\nplease input the name of file where data is stored,end with enter key.\n");
    gets(DataFile);
    /*提示教师输入要进行修改记录的文件名*/
    while(*DataFile == ('\0'))
    {
        printf("\nplease input the name of file where data is stored,end with enter key.\n");
        gets(DataFile);
    }
begin:
    /*以读的方式打开文件，如文件不存在，提示错误*/
    fp=fopen(DataFile,"rb");
    if (fp == NULL)
    {
        printf("\nOpen file %s fail!End with any key\n",DataFile);
        perror("Open file fail");
        getch();
        exit(1);
    }
    printf("please input the Employee'seatnum which you will modify:");
    scanf("%ld",&modnum);
    printf("the student you will delete is:%ld\n",modnum);
    /*输入要修改记录的各项内容值*/
    Number=modnum;
    printf("name=");
    scanf("%s",Name);

    printf("chinesescore=");
    scanf("%f",&chinesescore);

    printf("mathscore=");
    scanf("%f",&mathscore);

    /*用公式自动计算学生总分*/
    heji=chinesescore+mathscore;
   /*将文件中要修改的信息存入结构体数组*/
   recNumber=0;
   /*循环将文件数据读入结构体数组，
   如文件中的数据学生号和要修改的学生号不符，则原样写入数组，
   如文件中数据的学生号和要修改学生号匹配，
   则根据教师输入的各项修改内容重新赋值，即修改，并写入数组*/
    while((fread(&TmpS,sizeof(student),1,fp)) != (int)NULL)
    {
        if(TmpS.Number!=modnum)
            {
            s[recNumber].Number = TmpS.Number;
            strcpy(s[recNumber].Name, TmpS.Name);
            s[recNumber].chinesescore = TmpS.chinesescore;
            s[recNumber].mathscore = TmpS.mathscore;
            s[recNumber].heji = TmpS.heji;
            recNumber++;
            }
        else
            {
            s[recNumber].Number = Number;
            strcpy(s[recNumber].Name, Name);
            s[recNumber].chinesescore = chinesescore;
            s[recNumber].mathscore = mathscore;
            s[recNumber].heji = heji;
            recNumber++;
            }

    }
    fclose(fp);
   /*====将修改后的结构体数组记录写入文件====*/
        fp=fopen(DataFile,"wb+");
        if (fp == NULL)
        {
            printf("\nSet up file %sfail !end with anykey.\n",DataFile);
            perror("Set up fail");
            getch();
            exit(1);
        }


        for(i=0; i<recNumber; i++)
        {
            if(fwrite(&s[i],sizeof(student),1,fp)!=1)
            {
                printf("\nWrite file %s fail!end with anykey.\n",DataFile);
                perror("Write file fail!");
                    getch();
                    exit(1);
            }
        }
        fclose(fp);
     /*====显示修改后的文件====*/
    fp=fopen(DataFile,"rb");
    if (fp == NULL)
    {
        printf("\nOpen file%sfail!End with any key \n",DataFile);
        perror("Open file fail");
        getch();
        exit(1);
    }
    printf("the file after modify is:\n");
    printf("\nNumber \t\tName\tchinesescore\tmathscore\theji\n");
    while(fread(&TmpS,sizeof(student),1,fp) != (int)NULL)
    {
        if(TmpS.Number!=0)
        printf("\n%ld\t        %s\t   %5.2f\t  %5.2f\t%5.2f\n",TmpS.Number,TmpS.Name,TmpS.chinesescore,TmpS.mathscore,TmpS.heji);
    }
    fclose(fp);
/*提示是否进行下一次修改*/
    printf("\nGo on ?(y/n)");
    next=getche();
    putchar('\n');
    if ( next =='y' || next =='Y') goto begin;
 }