#include <iostream>#include <string>#include <fstream>using namespace std;int readfile(void);int main(int argc, char *argv[]){ int choice = 0; cout<< "Press 2 to show hello world!: Press 3 to show hello name from a file, and press 1 to show the menu again"<<endl; cin>>choice; switch (choice) { case 1: cout<< "Press 2 to show hello world!: Press 3 to show hello name from a file, and press 1 to show the menu again"<<endl; case 2: cout<< "Hello World! "<<endl; case 3: readfile(); case 4: break; }}int readfile(void) { ifstream fin; string name = ""; fin.open ("helloworld.txt"); if (fin.fail()) { cout<<"Error could not open file!" <<endl; } getline(fin, name); if (name == "") { cout<< "Hello World!"<<endl; } else { cout<< "Hello " << name << "!" << endl; } fin.close(); return 0; }