使用C将文件从一个目录复制到另一个目录。在发送目录中打开文件时出现问题。无此文件或目录

I am brand new to System Programming and am having some trouble learning how directories and files work. The program should take two arguments(directories), if both are existing directories then just copy the files from the first argument into the second. If the second is a file, return with an error, finally if the second argument doesn't exist, then create it and copy the files over.I am brand new to System Programming and am hav