App and avoiding goto

Question

ndowens 0 Newbie Poster

13 Years Ago

I am writing a application for Arch Linux, actually I already wrote it, but I wanted to do it a little differently then the other. The origional one uses the goto statement. Here is the code:

#include <iostream>
#include <string>
using namespace std;

int main()
{
   cout
    << "\tAurDown v2.1\n"

    << "\tLicense: GPL3\n\n"
    << "Menu\n"
    << "1. Search for package\n"
    << "2. Download a package\n";
   cout << "Enter Selection\t";
   cin >> nSel;
 
  while((nSel != 1) || (nSel != 2))
    {
   cout << "Please Enter a valid selection"\n;
   cin >> nSel;
         
    }
}

I am wanting to it to print "Please enter a valid selection" as many times as somebody enters anything other than 1 or 2 and if the person enters 1 or two after they get the error "Please enter a valid...." it will resume. Sorry this is a newbie question. I know it has to be a simple problem, but can't find it.

Thanks

c++ goto loop

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9 Replies
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Latest Post 13 Years Ago Latest Post by jonsca

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sfuo 111 Practically a Master Poster

13 Years Ago

First of all you havent declared nSel any where but you are using it, so put int nSel = 0; before the cout lines or something (just before usage).

Then for your while loop you should make it so it loops while nSel is not 1 AND 2 not or. while((nSel != 1) && (nSel != 2))

ndowens commented: Helped me with my code issue +1

triumphost 120 Posting Whiz

13 Years Ago

You can use cases..

#include <iostream>
#include <string>
using namespace std;

char nSel;
void getinput();

int main()
{
   cout
    << "\tAurDown v2.1\n"

    << "\tLicense: GPL3\n\n"
    << "Menu\n"
    << "1. Search for package\n"
    << "2. Download a package\n";
   cout << "Enter Selection\t";
   getinput();
return 0;
}


void getinput()
{
     cin>>nSel;
     cin.ignore();
     switch(nSel)
     {
              case '1': cout<<"You chose to Search for a package\n";  //U can put anything here...
                        break;
              case '2': cout<<"You chose to download a package\n";
              break;
              default: cout<<"Please Enter a valid selection\n";
                       getinput();
              break;
     }     
}

That should definitely work.. If the user presses

1.. it prints they selected to search.
2.. It prints the selected to download..

Anything else, It prints "Please Enter a valid selection" and lets them choose again.. if they enter anything else again, it just repeats until they enter a valid selection such as 1 or 2.

The function "getinput();" is a prototype function.. But prototype functions work wonders.. especially in situations like these!

Edited 13 Years Ago by triumphost because: n/a

jonsca 1,059 Quantitative Phrenologist

13 Years Ago

The function "getinput();" is a prototype function..

I've never heard the term used like that. What exactly does it imply?

Also, what could be considered an opinion or design choice, but the do/while loop avoids the potential stack issues with the recursive function.

Edited 13 Years Ago by jonsca because: n/a

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ndowens 0 Newbie Poster · Answer 1 · 2011-02-04T11:42:15+00:00

ndowens 0 Newbie Poster

13 Years Ago

Ah thanks so much

Ancient Dragon 5,243 Achieved Level 70 Team Colleague Featured Poster · Answer 2 · 2011-02-04T15:51:31+00:00

Ancient Dragon 5,243 Achieved Level 70

13 Years Ago

Maybe he's thinking Java

mitrmkar 1,056 Posting Virtuoso · Answer 3 · 2011-02-04T16:00:34+00:00

The function "getinput();" is a prototype function.. But prototype functions work wonders.. especially in situations like these!

I'm guessing that triumphost meant to say function prototype

jonsca 1,059 Quantitative Phrenologist Team Colleague Featured Poster · Answer 4 · 2011-02-04T16:28:35+00:00

That's what I was thinking, too, but it doesn't make sense in the context. LOL I guess we'll have to wait and see what he says.

triumphost 120 Posting Whiz · Answer 5 · 2011-02-06T08:40:19+00:00

triumphost 120 Posting Whiz

13 Years Ago

yes I meant function prototype..

That is how you use it :S
I've used that code and it compiled perfectly. No ancient.. I meant c++
See the managed attachments for examples of the code in action..
Written by myself of course but yeah I meant function prototypes.. for some reason I always call it prototype function :S

Patcher.cpp (3.84 KB)

//PatcherScript
#include <iostream>
#include <windows.h>

using namespace std;

char x,y,z;

void RegRun();
void saymsg();
void getinput();
void askagain();
void start();       

int main()
{
    /*system("\"C:/Program Files/Alwil Software/Avast5/AvastUI.exe\"");*/        //Commented out for compatibility reasons; Added to Reg Key.
	SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 13);
    cout<<"Please Install Avast Included with this Program!\n";
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 14);
	cout<<"If already installed ignore the message above and continue..\n";
	SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 15);
	system("PAUSE");
	cout<<"\n";
	SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 9);
    cout<<"System Registry must be Edited Once more to remove the Last Key!\n";
    cout<<"And add a New one which will be deleted later\n\n";
    start();
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 10);
    cout<<"Editing Finished According To User:\n";
    system("shutdown -r");
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 15);
    cout<<"Restarting Computer in 60 Seconds\n\n";
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 11);
    cout<<"PRESS F8 REPEATEDLY WHEN THE COMPTUER RESTARTS TO GET INTO SAFEMODE!!\n\n";
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 12);
    cout<<"SAFEMODE IS A MUST!! FOR YOUR OWN SYSTEM'S PROTECTION!\n";
    system("PAUSE");
    
    return 0;
}


     //Functions(1) Defined After Main and Before Main as Prototypes... Taken from old project "test cases.cpp" & Modified to Suit...


                                             
void RegRun()
{
     system("C:/Windows/RunOnce2.reg");
}

void saymsg()
{
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 10);
     cout<<"Did you press yes to edit the registry this time?\n";
}

void getinput()
{
     cin>>x;
     cin.ignore();
     switch(x)
     {
              case '1': false;
                        break;
              case '2': askagain();
              break;
              default: SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 12);
                       cout<<"You entered A letter or character that is not in the menu\n";
                       cout<<"Please try again!\n";
                       SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 15);
                       cout<<"Did you press yes to allow registry editing?  y = 1  n = 2\n";
                       getinput();
              }     
}
void askagain()
{
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 10);
     cout<<"Would you like to try editing the registry again?? 1 = Yes , 2 = No just exit!\n";
                   cin>>y;
                   cin.ignore();
                   switch(y){
                             case '1': 
                                  RegRun();
                                  saymsg();
                                  getinput();
                                  break;
                             case '2': exit(0);      // want to make the program terminate... tried return 0 but it failed...
                             break;
                             default: SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 12);
                                      cout<<"You entered A letter or character that is not in the menu\n";
                                      cout<<"Please try again!\n";
                                      askagain();
                             break;
                             }
                   }
                   
void start()
{
     RegRun();
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 15);
     cout<<"Did you press yes to allow registry editing?   y = 1   n = 2\n";
     getinput();
}

PatchScript2.cpp (2.78 KB)

//PatcherScript2
#define _WIN32_IE		0x0500
#include <windows.h>
#include <lm.h>
#include <assert.h>
#include <iostream>
#include <winuser.h>
#include <stdlib.h>
#include <string>
#include <stdio.h>
#include <fstream>
#include <algorithm>
#include <shlobj.h>
#include <direct.h>
#include <windows.h>
#include <Shellapi.h>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <winable.h>
#pragma comment(lib, "Netapi32.lib")

using namespace std;

char x;
void continueprog();
void remove();
void movefile();

int main()
{
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 14);
    cout<<"IF U ARE NOT IN SAFEMODE, EXIT THIS PROGRAM NOW!! AND DO IT!\n"; 
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 15); 
    system("PAUSE");
    cout<<"\n";
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 11);
    cout<<"Checking if Processes were killed!\n";
    system("taskkill /F /T /IM AvastUI.exe");
    cout<<"\n\n";
    SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 12);
    cout<<"NOTE: IF Process is NOT FOUND, CONTINUE! If Process Cannot be TERMINATED,\n";
    cout<<"You must RETRY stopping all services!\n\n";
    continueprog();
    
    
    BlockInput(true);
    Sleep(5000);
    BlockInput(false);
    
    Sleep(5000);
}

void continueprog()
{
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 10);
     cout<<"Continue = 1  ,  Retry = 2\n";
     cin>>x;
     cin.ignore();
     switch(x)
     {
              case '1': cout<<"Continuing\n";
                        remove();
                        movefile();
                        break;
              case '2': cout<<"Retrying.. Please Follow the Instructions on Screen\n";
                        main();
                        break;
              default:  cout<<"You chose an option/character that is not on the menu, retry\n\n";
                        continueprog();
                        break;
                        }
}


void remove()
{
     if( remove( "C:\\Program Files\\Alwil Software\\Avast5\\ashBase.dll" ) != 0 ){
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 12);
     perror( "Error deleting Old Ashbase.dll\n" );
     }
     else{
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 10);
     puts( "Old Ashbase.dll successfully deleted\n" );
     }
}

void movefile()
{
     if ( rename("C:\\Windows\\ashBase.dll", "C:\\Program Files\\Alwil Software\\Avast5\\ashBase.dll") != 0){
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 12);
     perror( NULL );
     getchar();
     }
     else{
     SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE), 10);
     puts( "Ashbase.dll Replaced Successfully\n" );
     Sleep(5000);
     }
     exit(0);
}

Edited 13 Years Ago by triumphost because: n/a

jonsca 1,059 Quantitative Phrenologist Team Colleague Featured Poster · Answer 6 · 2011-02-06T08:57:06+00:00

I don't quite understand how it "worked wonders" then. Unless you've got your function definitions out ahead of main(), there should always be prototypes. Anyway, thanks for clarifying it.

App and avoiding goto

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