程序代码：

void modify(int number)          //修改
{
    FILE * fp1;
    int n=0;

    if((fp = fopen("bookinfo.txt","r")) == NULL){
        printf("File open error!\n");
        exit(0);
        }
    while(!feof(fp))
    {    
        for(;!feof(fp);){
            fscanf(fp, "%d %s %s %f", &num, writer, name, &price);
            if(number != num)
            {
                if((fp1 = fopen("temp.txt","a+"))==NULL){
                    printf("open error!\n");                        exit(0);
                }
                fprintf(fp1, "%d %s %s %f ", num, writer, name, price);
                fclose(fp1);
            }
            if(number == num)
                    n ++;
        }
            
    }
    
    printf("请输入新图书编号");
    scanf("%d", &num);
    check(num);
    printf("请输入新图书名:");
    scanf("%s", name);
    printf("请输入新图书作者:");
    scanf("%s", writer);
    printf("请输入新图书价格:");
    scanf("%f", &price);
    if((fp1 = fopen("bookinfo.txt","a+"))==NULL){
        printf("open error!\n");
        exit(0);
    }
    if(n == 0){
        printf("无此图书!\n");
        exit(0);
    }
    fprintf(fp1, "%d %s %s %f ", num, writer, name, price);
    fclose(fp1);
    fclose(fp);
    wenjian(fp, fp1);
    printf("修改完成!\n");
    main();
    
}
void wenjian(FILE *fp, FILE *fp1)
{    

    system("rename bookinfo.txt temp1.txt");
    system("rename temp.txt bookinfo.txt");    
    remove("temp1.txt");[local]1[/local]
}

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