程序代码：

typedef struct list
{
    int number;
    char name[20];
    char writer[20];
    float price;
    char date[20];
    int state;
}LIB;
char *fn1="d:\\num.txt",*fn2="d:\\data.txt";
FILE *fp1,*fp2;
void shanchu()
{
    LIB *p;
    int num,i,j;
    num=fornum();
    fp2=fopen(fn2,"r");
    p=(LIB*)malloc(num*sizeof(LIB));
    fread(p,sizeof(LIB),num,fp2);
    fclose(fp2);
    for(i=0;i<num;i++)
        printf("\t%d\t%s\t%s\t%.1f\t%s\t%c\n",(p+i)->number,(p+i)->name,(p+i)->writer,(p+i)->price,(p+i)->date,(p+i)->state);
    printf("请输入您想删除内容的对应序号\n");
    scanf("%d",&i);i--;
    fflush(stdin);
    for(j=i;j<num-1;j++)
    {
        (p+j)=(p+j+1);//这里提示有错误:left operand must be l-value
    }
    free(p);
    num-=1;
    fp1=fopen(fn1,"w");
    fprintf(fp1,"%d",num);
    fclose(fp1);
}