C语言读写文件函数:read/write,pread/pwrite,readv/writev,preadv/pwritev,preadv2/pwritev2
函数原型//最基本的read,write函数//read,write-readfromorwritetoafiledescriptor#includessize_tread(intfd,void*buf,size_tcount);ssize_twrite(intfd,constvoid*buf,size_tcount);//在read,write函数基础上,可指定位置偏移量//pread,pwri