C语言代码片段-读写标准输入流

#include<unistd.h>
#define SIZE 100

int main()
{
    int n;
    char buf[SIZE];
    while(n=read(STDIN_FILENO,buf,SIZE))
    {
        if(n!=write(STDOUT_FILENO,buf,n))
             perror("write error");
    }
    if(n<0) perror("read error");
    return 0;
}