Question

我正在为一本简单的电话簿编写代码。一切正常，除了使用我的删除功能成功删除条目后，我的追加功能似乎不再写入文件的条目了。除非我删除了我用来存储条目的database.data文件。

注意：字符数组文件=＆＃34; database.data＆＃34;

删除功能：

void deletee()
{


  int tode,count;
    char ch;
    printc();
    count=1;

    FILE *filepointer,*filepointer2;

    filepointer=fopen(file,"r+");
    filepointer2=fopen("datatemp.data","w+");
    if(filepointer==NULL)
    {
        printf("ERROR ERROR!");
    }

    printf("Enter line number of the line to be deleted: \n");
    scanf("%d",&tode);
    while (ch!=EOF)
    {
        ch=getc(filepointer);
        if(ch=='\n')
        {
            count++;
        }
        if(count!=tode)
        {
                fprintf(filepointer2,"%c",ch);
        }
    }
fclose(filepointer);
fclose(filepointer2);
remove(file);
rename("datatemp.data",file);
printf("Content successfully deleted!!");

}

继承人追加功能：

void append(struct entry *ptr)
{

FILE *filepointer;

filepointer=fopen(file,"a+");

    fflush(stdin);              //This block is asking for the inputs to be placed into the file
    printf("Enter FName: ");
    scanf("%s",&ptr->fn);
    printf("\nEnter LName: ");
    scanf("%s",&ptr->ln);
    printf("\nEnter MName: ");
    scanf("%s",&ptr->mn);
    printf("\nEnter BD: ");
    scanf("%s",&ptr->bd);
    printf("\nEnter CNum: ");
    scanf("%s",&ptr->cn);

if(filepointer==NULL)
{
    printf("The file does not exist.\n");
    return;
}

    system("cls");
    fprintf(filepointer,"%15s%15s%15s%9s%11s\n",ptr->fn,ptr->ln,ptr->mn,ptr->bd,ptr->cn);
    fclose(filepointer);
    printf("Entries successfully written!\n");
}

结构条目 {

  char fn[15];
    char ln[15];
    char mn[15];
    char bd[9];
    char cn[11];
}p;

如果您想了解更多详情，请告诉我。

UPDATE -

我将问题缩小到删除函数中的while循环，如果while循环中的内容是这样写的话，我的append函数似乎在使用delete后工作：

    while (ch!=EOF)
    {
        ch=getc(filepointer);
        if(count!=tode)
        {
                fprintf(filepointer2,"%c",ch);
            if(ch=='\n')
            {
                count++;
            }
        }
    }

但是如果以这种方式编写while循环，它将删除指定行之后的所有条目。而在我之前的删除函数中的while循环代码中，它只删除了该特定行，但如上所述，追加函数无法写入文件的问题将持续存在，直到我删除文件＆＃34;数据库。数据＆＃34;手动

Answer 1

解决问题的结果是append函数能够将条目写入文件唯一的问题是我的print函数无法打印出新条目，因为delete函数在执行后留下了垃圾。修改了代码，以便在删除后不会写入垃圾。

void deletee（）

{

    int tode,count;
    char ch,sc;
    printc();
    count=1;

    FILE *filepointer,*filepointer2;

    filepointer=fopen(file,"r+");
    filepointer2=fopen("datatemp.data","w+");
    if(filepointer==NULL)
    {
        printf("ERROR ERROR!");
    }
    printf("Enter line number of the line to be deleted: \n");
    scanf("%d",&tode);
    while (ch!=EOF)
    {
        ch=getc(filepointer);
        if(count!=tode)
        {
                if(ch==EOF)
                    {
                    break;
                    }
                fprintf(filepointer2,"%c",ch);

        }
            if(ch=='\n')
            {
                count++;
            }

    }
fclose(filepointer);
fclose(filepointer2);
swap();
remove("datatemp.data");
printf("Content successfully deleted!!");

}

为什么我的追加功能不再写入文件

1 个答案: