编写一个类，该类具有统计文件长度，实现文件复制的函数。 其中复制功能函数如： void copy(string srcFileName,string targetFileName);

#include"iostream"#include"string"#include"fstream"using namespace std;class file{private:static int length;public:file(){};static void copy(string srcFileName,string targetFileName);void getlength(){cout << "文件长度为：" << length << endl ;}};void file::copy(string srcFileName,string targetFileName){char ch;cout << srcFileName << endl ;ifstream in(srcFileName.data(),ios::in|ios::binary);ofstream out(targetFileName.data(),ios::out|ios::binary);while(in.get(ch)){out.put(ch);length++;}in.close();out.close();}int file::length=0;void main(){file f;string srcFileName,targetFileName;cout << "请输入源文件名(格式：磁盘名:\\文件名.文件格式)" << endl ;cin >> srcFileName;cout << srcFileName << endl ;cout << "请输入目标文件名(格式：磁盘名:\\文件名.文件格式)" << endl ;cin >> targetFileName;f.copy(srcFileName,targetFileName);f.getlength();}