有以下程序: include <iostream.h> include <fstream.h> include <stdlib.h> int main() { fstream filel,file2; char line[100]; filel.open('source.txt',ios::in); if(!file1) { cout<<'Can't open file source.txt!'<<end1; abort(); } file2.open('dest.txt',ios::out); if(!file2) { cout<<'Can't open file dest.txt!'<<end1; abort(); } while(!file1.eof()) { filel.getline(1ine,100); file2<<line; file2<<end1; } filel.close(); file2.close(); return 0; } 此程序实现的功能是【 】。