Writing unsigned chars to a binary file using write()

I was making a program that read binary files. So, I read the individual bytes into unsigned chars (actually reading the data as chars and casting them to unsigned chars for each character). Now I have to write back the unsigned chars to the binary file.

The problem is that now I am forced to write individual bytes after casting them to chars (because write() for binary files expects char* buffer). So, now i have to do the following:

for(int x=0; x<data_size; x++)
{
    ch=(char)data[x];
    outfile.write(&ch,1);
}

Is there any way to get around this thing so that the amount of I/O operations are reduced in case of reading and writing?