如何在循环中写入 C 套接字中的二进制文件

Question

I have the following snippet where I read sent bytes using read() and store the data in a buffer which works well. But how do i make it so that I can continue to write in binary file after every read. My assumption is that it might have something to do with not resetting the buffer. Thanks for the help!

fp = fopen (filename, "wb"); //create a file

while (size > 0){        
    n = read(socket,buffer,size*sizeof(char));
    if (n <=0)
        return -1;
    p += n;
    size -= n;

    fwrite(buffer,sizeof(char),size*sizeof(char),fp); //write the content to the file

}

Answer 1

You should use n in the call to fwrite() , not size . n is the amount you just read from the socket, size is how many more bytes you're still waiting for.

fwrite(buffer,sizeof(char),n,fp);

You also shouldn't multiply by sizeof there. The second argument is the size of each element, the third argument is the number of elements; fwrite() performs the multiplication internally. It happens to work in your case because sizeof(char) is always 1 , so the multiplication didn't change anything.