Use the C language redirection function freopen to exchange two text files

/*** Autor: wangzhicheng *** E-mail: 2363702560@qq.com ** Date: 2012/10/4 ** description: swap two files */# include <iostream> # include <cstdlib> # include <cstdio> # include <string> using namespace STD; /* write the source file to the target file */inline static bool writetofile (string srcfilename, string desfilename) {file * stream; stream = freopen (srcfilename. c_str (), "r", stdin); // redirects the content of the source file to the standard input stream/*, which means that the standard input stream points to the file srcfilename. Reading the standard input stream is actually for srcfilena Me read */If (! Stream) return false; stream = freopen (desfilename. c_str (), "W", stdout); // redirects the content of the target file to the standard output stream./* this means that the standard output stream points to the file desfilename, writing to the standard output stream is actually writing to desfilename */If (! Stream) return false; char C; while (scanf ("% C", & C )! = EOF) printf ("% C", c); // read characters from the input stream, and then write to the output stream/* which means to read content from the source file, then write the target file */fclose (stdin); fclose (stdout); Return true;} inline static void swapfile (string & filename1, string & filename2) {string tmpfilename = "E: \ tmp.txt "; // specify the temporary file name cout <" Enter the first file name (full path): "; CIN> filename1; cout <"enter the second file name (full path):"; CIN> filename2; If (! Writetofile (filename1, tmpfilename) return; If (! Writetofile (filename2, filename1) return; If (! Writetofile (tmpfilename, filename2) return; cout <"file exchange successful! "<Endl;} void main () {cout <" written by wangzhicheng! "<Endl; string filename1, filename2; swapfile (filename1, filename2 );}