读入文件List.txt:

名称     品牌     价格     数量
phone     huawei     2000.000000     35
clothes     supreme     900.000000     8
shoes     lining     800.000000     10
fan     haier     500.000000     5 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 15
typedef struct product
{char name[N];char brand[N];int amount;double price;struct product *next;
}PRO;
/*生成一个新的节点，并为该节点赋初值，返回指向新节点的指针*/
PRO *Createnode()
{PRO *p;p=(PRO *)malloc(sizeof(PRO));if(p==NULL){printf("NO enough memory!\n");exit(0);}p->next=NULL;strcpy(p->name," ");strcpy(p->brand," ");p->amount =0;p->price=1;return p;
}
void Insertdata(PRO *head)//用于进货，同时考虑到进同一商品的问题
{PRO *p = head,*s = head,*q;p = Createnode();printf("请输入进货的名称、品牌、价格和数量：\n");scanf("%s %s %lf %d",p->name,p->brand,&p->price,&p->amount);if(head->next ==NULL){head->next = p;}else{while((p->price)<(s->next->price)){s=s->next;if(s->next==NULL){break;}}if(s->next !=NULL){if(strcmp(p->name,s->next->name)==0&&strcmp(p->brand,s->next->brand)==0){s->next->amount+=p->amount;}else{q = s->next;s->next = p;p->next = q;}}else{s->next = p;p->next = NULL;}}
}
void Deletedata(PRO *head)//用于提货，同时考虑到库存不够的问题
{PRO *q = head,*p = head,*s,*r;p = Createnode();printf("请输入取货的名称、品牌、价格、数量：\n");scanf("%s %s %lf %d",p->name,p->brand,&p->price,&p->amount);if(head->next==NULL){printf("暂无库存！\n");}else{while(strcmp(q->next->brand,p->brand)!=0||strcmp(q->next->name,p->name)!=0){q = q->next;if(q->next ==NULL){break;}}if(q->next !=NULL){if(q->next->amount == p->amount){if(q->next->next==NULL){s = q->next;q->next=NULL;free(s);}else{s = q->next->next;r = q->next;q->next = s;free(r);}}else{if(q->next->amount <p->amount)printf("库存不够！请重新选择操作！\n\n");elseq->next->amount -=p->amount;}}else{if(p->amount==q->amount){free(q);}elseq->amount -=p->amount;}}
}
void Printdata(PRO *head)//打印库存商品信息
{PRO *p=head->next;printf("名称\t品牌\t单价\t\t数量:\n");while(p!=NULL){printf("%s\t%s\t%lf\t%d\n",p->name,p->brand,p->price,p->amount);p = p->next;}printf("\n\n");
}
void Updatedata(PRO *head)
{PRO *p,*q=head,*s;p = Createnode();printf("请输入变动产品的名称、品牌、现价和数量：\n");scanf("%s %s %lf %d",p->name,p->brand,&p->price,&p->amount);while(strcmp(q->next->brand,p->brand)!=0||strcmp(q->next->name,p->name)!=0){q=q->next;}if(q->next->next==NULL){s = q->next;q->next = p;p->next = NULL;free(s);}else{s = q->next;p->next = s->next;q->next = p;free(s);}
}
int Menu()
{int x;printf("家电营业系统：\n");printf("1.营业开始\n");printf("2.进货\n");printf("3.提货\n");printf("4.更新信息\n");printf("5.查询信息\n");printf("6.退出系统\n\n");printf("请选择你要执行的操作：\n");scanf("%d",&x);return x;
}
void Readfile(PRO *head)//从List.txt中读入数据
{FILE *fp;PRO *p=head,*q;q=Createnode();char name[N],brand[N];int price=0,amount=0;fp=fopen("List.txt","r");if(fp==NULL){printf("读取文件List.txt失败！\n");exit(0);}fseek(fp,22,0);while(fscanf(fp,"%s",q->name)!=EOF){fscanf(fp,"%s",q->brand);fscanf(fp,"%lf",&q->price);fscanf(fp,"%d\n",&q->amount);p->next=q;p=q;q=Createnode();}p->next=NULL;fclose(fp);
}
int Savefile(PRO *head)//保存数据
{FILE *fp;PRO *p=head->next;fp=fopen("List.txt","w");if(fp==NULL){printf("写入文件List.txt失败！\n");return -1;}fprintf(fp,"名称\t 品牌\t 价格\t 数量\n");while(p!=NULL){fprintf(fp,"%s\t %s\t %lf\t %d\n",p->name,p->brand,p->price,p->amount);p=p->next;}fprintf(fp,"\n");fclose(fp);return 0;
}
void Createlist(PRO *head)
{Readfile(head);printf("营业开始，请继续选择需要执行的操作：\n");
}
int main()
{PRO *head;char ch;head=Createnode();printf("注意：首次进入系统必须选择1号！\n");while(1){ch = Menu();switch(ch){case 1:Createlist(head);break;case 2:Insertdata(head);break;case 3:Deletedata(head);break;case 4:Updatedata(head);break;case 5:Printdata(head);break;case 6:printf("营业结束！数据已保存至文件！");Savefile(head);exit(0);default:printf("请输入正确序号!\n");}}return 0;
}