新手求助

aavivian

哪位前辈能帮我看看，为什么我写的两个文件复制的程序，复制结果总是有错误呢？

#include<stdio.h>
#include<sys/types.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>
#include<sys/stat.h>

#define readmsg 200

int main(int argc,char *argv[])
{
  int srcfd,aimfd,length;
  int readlength=0;
  int location;
  char buf[readmsg];
  if(argc!=3)
  {
    printf("Less of parament!\n");
    printf("Please input the command as follow form!\n");
    printf("ProgramName+SourceFileName+AimFileName.\n");
    exit(0);
  }
  if((srcfd=open(argv[1],O_RDONLY))==-1)
  {
    printf("Fail to open SourceFile!\n");
    exit(1);
  }
if((aimfd=open(argv[2],O_RDWR|O_CREAT,0333))==-1)
  {
    printf("Fail to open AimFile!\n");
    exit(1);
  }
  length=lseek(srcfd,0,SEEK_END);
  printf("The lenth of SourceFile is %d bytes!\n",length);
  location=lseek(srcfd,0,SEEK_SET);
  while(length>readmsg)
    {
      if(readlength=(read(srcfd,buf,readmsg))==-1)
      {
        printf("Read SourceFile failure!\n");
        exit(1);
      }
      if((write(aimfd,buf,readmsg))==-1)
      {
        printf("Write to AimFile failure!\n");
        exit(1);
      }
      location=lseek(srcfd,readmsg,SEEK_CUR);
      length=length-readmsg;
    }
  printf("Location is %d from the head of the file!\n");
  printf("Now the VAR length is %d!\n",length);
  read(srcfd,buf,length);
  printf("The messages read from the source file are\n%s\n",buf);
  write(aimfd,buf,length);
  close(srcfd);
  close(aimfd);
  exit(0);
}

xiyoulaoyuanjia

1. #include<stdio.h>
   
2. #include<sys/types.h>
   
3. #include<fcntl.h>
   
4. #include<unistd.h>
   
5. #include<stdlib.h>
   
6. #include<sys/stat.h>
   
7. 
   
8. #define readmsg 200
   
9. 
   
10. int main(int argc,char *argv[])
    
11. {
    
12.   int srcfd,aimfd,length;
    
13.   int readlength=0;
    
14.   int location;
    
15.   char buf[readmsg];
    
16.   if(argc!=3)
    
17.   {
    
18.     printf("Less of parament!\n");
    
19.     printf("Please input the command as follow form!\n");
    
20.     printf("ProgramName+SourceFileName+AimFileName.\n");
    
21.     exit(0);
    
22.   }
    
23.   if((srcfd=open(argv[1],O_RDONLY))==-1)
    
24.   {
    
25.     printf("Fail to open SourceFile!\n");
    
26.     exit(1);
    
27.   }
    
28. if((aimfd=open(argv[2],O_RDWR|O_CREAT,0333))==-1)
    
29.   {
    
30.     printf("Fail to open AimFile!\n");
    
31.     exit(1);
    
32.   }
    
33.   length=lseek(srcfd,0,SEEK_END);
    
34.   printf("The lenth of SourceFile is %d bytes!\n",length);
    
35.   location=lseek(srcfd,0,SEEK_SET);
    
36.   while(length>readmsg)
    
37.     {
    
38.       if(readlength=(read(srcfd,buf,readmsg))==-1)
    
39.       {
    
40.         printf("Read SourceFile failure!\n");
    
41.         exit(1);
    
42.       }
    
43.       if((write(aimfd,buf,readmsg))==-1)
    
44.       {
    
45.         printf("Write to AimFile failure!\n");
    
46.         exit(1);
    
47.       }
    
48.   //    location=lseek(srcfd,readmsg,SEEK_CUR);
    
49.       length=length-readmsg;
    
50.     }
    
51.   printf("Location is %d from the head of the file!\n");
    
52.   printf("Now the VAR length is %d!\n",length);
    
53.   read(srcfd,buf,length);
    
54.   printf("The messages read from the source file are\n%s\n",buf);
    
55.   write(aimfd,buf,length);
    
56.   close(srcfd);
    
57.   close(aimfd);
    
58.   exit(0);
    
59. }

复制代码

aavivian

十分感谢前辈。您的回复犹如醍醐灌顶啊！