C 从文件中删除一行不起作用

Question

我的 C 程序有问题。我想从文件中删除选定的行。对于两个文件，删除工作正常，但删除程序后不会更改文件名，也不会删除“旧”文件。

文件结构

"new","new","new","1001" 
"asd","as","das","asd" 
"sdasda","asasd","dsaa","sdsda" 

代码:

#include <stdio.h>
#include <stdlib.h> 
#include <string.h>
#include <time.h>

#define DB "db.txt" 

int main()
{
                    FILE *f1;
                    FILE *f2;
                    char ch;
                    int linia, tmp = 1;
                    f1 = fopen(DB, "r"); 
                    printf(" \n Enter line number:"); 
                    scanf("%d", &linia);
                    f2 = fopen("kopia.txt", "a+");
                    ch = getc(f1);
                    while (ch != EOF)
                    {
                        ch = getc(f1);
                        if (ch == '\n')
                            {       tmp++;      }      
                        if (tmp != linia)
                            {putc(ch, f2);}
                    }
                    fclose(f1);
                    fclose(f2);
                    remove(DB); //not working
                    rename("kopia.txt",DB); //not working
                    printf("\n Done:\n");

                    return 0;
}

Answer 1

  ...
  int ch;
  while (1)
  {
    ch = getc(f1);
    if (ch == EOF) break;
    if (ch == '\n') tmp++;     
    if (tmp != linia) putc(ch, f2);
  }
  ...