smprice.c

初始的商品信息文件名为porduct

 /* smemberprice.c：按商品会员价循序排序*/
#include "stdio.h"
void SortByMemberPrice()
 {
    int i,j,k;
    product TmpS;   /*定义进行操作时的临时结构体变量*/
    product s[SIZE];/*SIZE，在shead.h头文件中定义的常量，值为100  */
    int recNumber = 0;
    char DataFile[40] = ""; /*DataFile存储商品信息的文件名*/
    FILE *fp;/*====fp指针指向存储数据的文件名====*/
    /*提示顾客输入要进行排序的文件名*/
    printf("\nplease input the name of product information file.\n");
    gets(DataFile);
    /*提示顾客输入要进行排序的文件名*/
    while(*DataFile == ('\0'))
    {
        printf("\nplease input the name of product information file.\n");
        gets(DataFile);
    }
    /*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);
    }
   /*将文件中要排序的信息存入结构体数组*/
    while((fread(&TmpS,sizeof(product),1,fp)) != (int)NULL)
    {
        s[recNumber].Number = TmpS.Number;
        strcpy(s[recNumber].Name, TmpS.Name);
        s[recNumber].price = TmpS.price;
        s[recNumber].discount = TmpS.discount;
        s[recNumber].memberprice=TmpS.memberprice;
        recNumber++;
    }
    fclose(fp);
    /*====如果文件中有记录，则将各条记录按合计值排序===*/
    if(recNumber>1)
    {
        /*====用选择排序法进行按合计的排序====*/
        for(i=0;i<recNumber-1;i++)
        {
            k = i;
            for(j=i+1;j<recNumber;j++)
            {
                if(s[k].memberprice<s[j].memberprice) k = j;
            }
            TmpS.Number = s[k].Number;
            strcpy(TmpS.Name,s[k].Name);
            TmpS.price = s[k].price;
            TmpS.discount = s[k].discount;
            TmpS.memberprice = s[k].memberprice;


            s[k].Number = s[i].Number;
            strcpy(s[k].Name,s[i].Name);
            s[k].price = s[i].price;
            s[k].discount = s[i].discount;
            s[k].memberprice = s[i].memberprice;

            s[i].Number = TmpS.Number;
            strcpy(s[i].Name,TmpS.Name);
            s[i].price = TmpS.price;
            s[i].discount = TmpS.discount;
            s[i].memberprice = TmpS.memberprice;
        }

        /*====将排序好的结构体记录写入文件====*/
        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(product),1,fp)!=1)
            {
                printf("\nWrite file %s fail!end with anykey.\n",DataFile);
                perror("Write file fail!");
                    getch();
                    exit(1);
            }
        }
        fclose(fp);
    }
     /*====显示排序后的文件====*/
    printf("the product's information in file %s is as flow:.\n",DataFile);

    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("\nNumber \tName\tprice\tdiscount\tmemberprice\n");
    while(fread(&TmpS,sizeof(product),1,fp) != (int)NULL)
    {
        printf("\n%ld\t%s\t%4.2f\t%4.2f\t%4.2f\n",TmpS.Number,TmpS.Name,TmpS.price,TmpS.discount,TmpS.memberprice);
    }
    fclose(fp);
}