记一次超市管理系统的开发

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define NUM 5



struct item{
    char brand[20];
    char id[10];
    float in_price;
    float out_price;
    int   storage;
};
struct item_node{
    struct item wanted;
    int    amount;
    struct item_node *next;
};

int menu();
void establish();
void dis_all();
void shop_cart();
int  cart_menu();
void add();
void display();
void calculate();

struct item goods[NUM];
struct item_node *cart;


main()
{
    printf("***********************************
");
    printf("     欢迎进入超市管理系统
");
    printf("***********************************
");
    while(1)
    {
        switch(menu())
        {
        case 1:
            establish();break;
        case 2:
            dis_all();break;
        case 3:
            shop_cart();break;
        case 4:
            calculate();break;
        case 5:
            printf("感谢使用，再见!
");
            exit(0);
        }
    }
}

int menu()
{
    char str[5];
    int  select;
    printf("

请选择数字进行操作
");
    printf("1.建立库存信息
");
    printf("2.显示所有信息
");
    printf("3.购物车
");
    printf("4.结算
");
    printf("5.退出
");
    printf("请选择对应数字1--5");
    while(1)
    {
        fflush(stdin);
        gets(str);
        select=atoi(str);
        if(select<1||select>5)
            printf("输入错误，请重新输入:");
        else
            break;
        
    }
    return select;
    
}

void dis_all()
{
    int i;
    FILE  *fp;
    fp=fopen("goods","r");
    for(i=0;(fread(goods+i,sizeof(struct item),1,fp))!=0;i++)
    {
        printf("---------------------------------
");
        printf("货品 品名  单价       库存量
");
        printf("%s%7s%7.2f%8d
",goods[i].id,goods[i].brand,goods[i].out_price,goods[i].storage);
        
    }
    fclose(fp);
}


void shop_cart()
{
    while(1)
    {
        switch(cart_menu())
        {
        case 1:
            display();break;
        case 2:
            add();break;
        case 3:
            return;
        }
    }
}
int  cart_menu()
{
    char  str[5];
    int   select;
    printf("
请选择操作
");
    printf("-----------------------
");
    printf("1.显示当前购物列表
");
    printf("2.添加商品
");
    printf("3.退出
");
    printf("-----------------------

");
    while(1)
    {
        fflush(stdin);
        gets(str);
        select=atoi(str);
        if(select<1||select>3)
            printf("输入错误，请重新输入:");
        else
            break;
    }
    return select;
}

void display()
{
    struct item_node *p=cart;
    if(p==NULL){
        printf("购物车为空
");
        return ;
    }
    while(p!=NULL){
        printf("----------------------------------
");
        printf("货号                品名  单价   数量
");
        printf("%10s%20s%7.2f%8d
",p->wanted.id,p->wanted.brand,p->wanted.out_price,p->amount);
        p=p->next;
    }
}

void add()
{
    FILE *fp;
    int   i,n;
    char  str[20];
    char  choice1,choice2;
    struct item_node *p,*p1;
    do
    {
        printf("输入所需物品的名称或货号: ");
        fflush(stdin);
        gets(str);
        if((fp=fopen("goods","r"))==NULL){
            printf("打开文件失败
");
            continue;
        }
        for(i=0;fread(goods+i,sizeof(struct item),1,fp)!=0;i++){
            if((strcmp(goods[i].brand,str)==0||strcmp(goods[i].id,str)==0)&&goods[i].storage!=0){
                printf("已经找到所需物品:  
");
                printf("---------------------
");
                printf("货号  品名  单价  库存量
");
                printf("%s%6s%3.2f%4d
",goods[i].id,goods[i].brand,goods[i].out_price,goods[i].storage);
                printf("请输入所需数量: ");
                scanf("%d",&n);
                if(n>goods[i].storage){
                    printf("库存不足
");
                    break;
                }
                printf("
是否购买?(Y/N)");
                fflush(stdin);
                choice1=getchar();
                if(choice1=='Y'||choice1=='y'){
                    p1=(struct item_node*)malloc(sizeof(struct item_node));
                    if(p1==NULL){
                        printf("内存申请失败!
");
                        exit(1);
                    }
                    p1->amount=n;
                    p1->wanted=goods[i];
                    p1->next=NULL;
                    p=cart;
                    if(cart==NULL)
                        cart=p1;
                    else{
                        while(p->next!=NULL)
                            p=p->next;
                        p1->next=p->next;
                        p->next=p1;
                    }
                }
                break;
            }
        }
        if(i==NUM)
            printf("未找到所需物品
");
        fclose(fp);
        printf("是否继续购物?(Y/N)");
        fflush(stdin);
        choice2=getchar();
    }while(choice2=='Y'||choice2=='y');
}


void  establish(){
    FILE *fp;
    int   i;
    printf("请依次输入货物信息:
");
    printf("----------------------------
");
    for(i=0;i<NUM;i++)
    {
        printf("品名: ");
        fflush(stdin);
        gets(goods[i].brand);
        printf("货号: ");
        fflush(stdin);
        gets(goods[i].id);
        printf("进价: ");
        fflush(stdin);
        scanf("%f",&goods[i].in_price);
        printf("哨价: ");
        fflush(stdin);
        scanf("%f",&goods[i].out_price);
        printf("数量: ");
        fflush(stdin);
        scanf("%d",&goods[i].storage);
        printf("
");
    }
    if((fp=fopen("goods","w"))==NULL){
        printf("创建文件失败.
");
        return;
    }
    fwrite(goods,sizeof(struct item),NUM,fp);
    fclose(fp);
}

void calculate()
{
    float total=0,pay;
    struct item_node *p;
    int   i;
    FILE   *fp;
    printf("以下是购物清单:  
");
    display();
    if((fp=fopen("goods","r"))==NULL){
        printf("打开文件失败:  
");
        return;
    }
    for(i=0;(fread(goods+i,sizeof(struct item),1,fp))!=0;i++);
    fclose(fp);
    p=cart;
    while(p!=NULL){
        total+=p->wanted.out_price*p->amount;
        for(i=0;strcmp(goods[i].id,p->wanted.id)!=0;i++);
        goods[i].storage-=p->amount;
        p=p->next;
    }
    printf("总计 %7.2f",total);
    printf("
输入实付金额: ");
    scanf("%f",&pay);
    printf("实付:         %7.2f    找零:          %7.2f",pay,pay-total);
    if((fp=fopen("goods","w"))==NULL){
        printf("打开文件失败.
");
        return;
    }
    fwrite(goods,sizeof(struct item),NUM,fp);
    fclose(fp);
}