C write() 函数不工作

Question

我正在尝试写入一个文件，但它不起作用。我可以打开一个文件，但是当使用 write 函数写入文件时，tt 正在写入 stdout 本身，而我打开的文件的内容保持不变。

#include<stdio.h>
#include<sys/file.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<limits.h>
#include<fcntl.h>
#include<stdlib.h>
#include<sys/uio.h> 
main() {  
  char fn[30]; 
  int fd,i=0; 
  int actualbytes,bytesstored; 
  char buffer[100];

  printf("\nEnter the filename with path"); 
  scanf("%s",fn); 

  if(fd=open(fn,O_WRONLY|O_CREAT,S_IWUSR|S_IWUSR)<0) 
  {  
     perror("open"); 
     exit(0); 
  } 
  else 
  {
    write(stdout,"\n\nEnter the contents for the file\n");  
    write(stdout,"press CTRl+D at the end of the file\n\n");

    fflush(stdout); 
    while((buffer[i]=getc(stdin))!=EOF)  i++;

    buffer[i]='\0'; 
    bytesstored=sizeof(buffer); 

    if(actualbytes=write(fd,buffer,bytesstored)<0)
    {  
       perror("write");  
       exit(0); 
    } 
    else 
    { 
       write(stdout,"\n\nfile is opened successfully");

       write(stdout,"\nThe contents are written"); fflush(stdout); 
    } 
    if(close(fd)<0) 
    {  
       perror("close");  
       exit(0); 
    } 
    else
       printf("\nfile is closed"); 
 } 
}

Answer 1

<优先级高于 = .

if((fd=open(fn,O_WRONLY|O_CREAT,S_IWUSR|S_IWUSR))<0)