小型商品管理系统（C语言实现）

/***************************************************/ /* modnum.c ：修改商品信息记录 */ /***************************************************/ #include "stdio.h" void ModifyByNumber() { int i,j,k; long modnum; /*存储顾客输入的要修改的商品序号*/ /*输入各项修改后信息*/ long Number; char Name[20]; float price; float discount; float memberprice; 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; char DataFile[40] = "",next; /*DataFile存储商品信息的文件名，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====*/ /*提示顾客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); /*提示顾客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 product 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("price="); scanf("%f",&price); printf("discount="); scanf("%f",&discount); /*用公式自动计算商品会员价*/ memberprice=price*discount; /*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， 如文件中的数据商品号和要修改的商品号不符，则原样写入数组， 如文件中数据的商品号和要修改商品号匹配， 则根据顾客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(product),1,fp)) != (int)NULL) { if(TmpS.Number!=modnum) { 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++; } else { s[recNumber].Number = Number; strcpy(s[recNumber].Name, Name); s[recNumber].price = price; s[recNumber].discount = discount; s[recNumber].memberprice = memberprice; 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(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\tprice\tdiscount\tmemberprice\n"); while(fread(&TmpS,sizeof(product),1,fp) != (int)NULL) { if(TmpS.Number!=0) printf("\n%ld\t%s\t%4.1f\t%4.1f\t%4.1f\n",TmpS.Number,TmpS.Name,TmpS.price,TmpS.discount,TmpS.memberprice); } 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; }