rendered paste body#include <iostream>#include <fstream>using namespace std;const int size = 30;char filename[size];//char menu;bool isNotvalidate(int);void choose(int);char ext[4];char newname[size+5];void extension(int, char ext[]);void append(char filename[], char ext[], char newname[]);int main(){ int choice; ifstream inputfile; do { cout << "What file contains your data? "; cin >> filename; cout << "1] .txt " << endl; cout << "2] .dat " << endl; cout << "3] .in " << endl; cout << "4] .ttd " << endl; cout << "What is the file extension?" << endl ; cin >> choice; }while(isNotvalidate(choice)); choose(choice);//SHows you the file extension you chose extension(choice, ext); append(filename, ext, newname); inputfile.open(newname);// open the file given cin.ignore(); cin.ignore(); return 0;}bool isNotvalidate(int choice){ if(choice < 1 || choice > 4) return true; else return false;}//char menu()//{//}void choose(int choice){ switch(choice) { case 1: cout << "Opening file " << filename << ".txt" << endl; break; case 2: cout << "Opening file " << filename << ".dat" << endl; break; case 3: cout << "Opening file " << filename << ".in" << endl; break; default: cout << "Opening file " << filename << ".ttd" << endl; break; }}void append(char filename[], char ext[], char newname[]){ for(int count=0; char filename[count] != '\0'; count++) newname[count] = filename[count]; for(int j=0; char ext[j] != '\0'; j++) newname[count] = ext[j]; newname[count] = '\0';}void extension(int choice, char ext[]){ if(choice == 1) char ext[] = '.txt'; else if(choice == 2) ext = '.dat'; else if(choice == 3) ext = '.in'; else if(choice == 4) ext = '.ttd';}