Question

我正在尝试使用原始I / O函数从文件中读取数据并将数据输出到另一个文件但是，似乎我的代码无法工作，我发现这是read（）无法终止。但是，我不知道如何终止循环，我的代码是这样的：

int main(){
   int infile; //input file
   int outfile; //output file

   infile = open("1.txt", O_RDONLY, S_IRUSR);
   if(infile == -1){
      return 1; //error
   }
   outfile = open("2.txt", O_CREAT | ORDWR, S_IRUSR | S_IWUSR);
   if(outfile == -1){
      return 1; //error
   }

   int intch; //character raed from input file
   unsigned char ch; //char to a byte

   while(intch != EOF){ //it seems that the loop cannot terminate, my opinion
      read(infile, &intch, sizeof(unsigned char));
      ch = (unsigned char) intch; //Convert
      write(outfile, &ch, sizeof(unsigned char));
  }
   close(infile);
   close(outfile);

   return 0; //success
}

有人可以帮我解决这个问题吗？你好多了

Answer 1

如果遇到文件结尾，

read将返回0：

while(read(infile, &intch, sizeof(unsigned char) > 0){ 
    ch = (unsigned char) intch; //Convert
    write(outfile, &ch, sizeof(unsigned char));
}

请注意，负值表示错误，因此您可能希望保存read的返回值。

Answer 2

intch是未初始化的4（或有时8个）字节。您只是将1个字节加载到intch中，并将剩余的字节保留为未初始化。然后，将EOF与所有未完全初始化的intch进行比较。

尝试将intch声明为char。

如何在c中停止从二进制文件中读取

2 个答案: