How do I stop a endless loop?

My program will load the main menu screen, but as soon as I input a menu selection it get stuck in an endless loop. Any help would be great!

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 /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/* 
 * File:   main.cpp
 * Author: Josh
 *
 * Created on February 5, 2018, 5:20 PM
 */

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

// Function Predeclarations

void menu();
void inputInfo(int i, string fname[3], string lname[3], string phoneNumber[3]);
void sort(string fname[3], string lname[3], string phoneNumber[3], string ascending);
void search(int i, string searchUser, string fname[3], string phoneNumber[3]);
void print(int i, string lname[3], string fname[3], string phoneNumber[3]);


int main()


{
   string fname[3]; 
   string lname[3];
   string phoneNumber[3];
   string ascending;
   int reply;
   string searchUser;
   int i;
   
do//this loop is set up to have the menu open after each function is completed
    {
        menu();
        
        cin >> reply;
        
        switch(reply)//set up menu with switch case using characters entered by user
        {
            case 'a':inputInfo(i, fname, lname, phoneNumber);
            break;
            
            case 'b':ascending = "y";sort(fname, lname, phoneNumber, ascending);
            break;
            
            case 'c':ascending = "n";sort(fname, lname, phoneNumber, ascending);//sorts arrays in descending order
            break;
            
            case 'd':print(i, fname, lname, phoneNumber);//prints arrays in their current state
            break;
            
            case 'e':search(i, searchUser, fname, phoneNumber);
            break;
        }
}
    while (reply != 'f');
    cout << "Goodbye" << endl;

    return 0;
}
// Function Implementations 
    
void menu()//prompts user to make a selection
{
    cout << "Welcome to your Contact Manager. Please select an option" << endl;
    cout << "a. Input Data" << endl;
    cout << "b. Sort Data Ascending" << endl;
    cout << "c. Sort Data Descending" << endl;
    cout << "d. Print All Data" << endl;
    cout << "e. Search for an individual in the data" << endl;
    cout << "f. End Program" << endl;
}

void inputInfo(int i, string fname[3], string lname[3], string phoneNumber[3])
{
    {
        for (i = 0; i < 2; i++)
    
    
     cout << "\nEnter Person's Name. Then press enter: ";
     cin >> fname[i];      // store the input directly in the array
     cout << "/nEnter Person's Last Name. Then press enter: ";
     cin >> lname[i];        
     cout << "Enter Phone Number. Then press enter: ";            // instead of using a dummy
     cin >> phoneNumber[i];
    }  
}

void sort(string fname[3], string lname[3], string phoneNumber[3], string ascending)
{
    string ptemp = "";
    string fntemp = "";
    string lntemp = "";
    int pass;
    int index;
    
    if(ascending == "y")
    {
        for (pass = 0; pass < 3; pass++)//create outer loop to count the number of passes
        {
            for (index = 0; index < 3 - pass; index++)//inner loop to iterate 10 times to account for all values
            {
                if (phoneNumber[index + 1] < phoneNumber[index])//if any value is moved the other two will also move inside their arrays
                {
                    ptemp = phoneNumber[index];
                    phoneNumber[index] = phoneNumber[index + 1];
                    phoneNumber[index + 1] = ptemp;
                    lntemp = lname[index];
                    lname[index] = lname[index + 1];
                    lname[index + 1] = lntemp;
                    fntemp = fname[index];
                    fname[index] = fname[index + 1];
                    fname[index + 1] = fntemp;
                }
            }
        }
        int index = 0;//prints out list after sorting
        cout << left << setw(12) << "Phone Number" << setw(5) << " " << setw(20) << "Last Name" << right << setw(20) << "First Name" << endl;  
        for(index = 0; index < 3; index++)   
        {
            cout << left << setw(12) << phoneNumber[index] << setw(5) << " " << setw(20) << fname[index] << right << setw(20) << lname[index] << endl;
        }
    }
  // Write the code descending order below: 
    }

void search(int i, string searchUser, string fname[3], string phoneNumber[3])
{
cout << "\nPlease enter the first name of the person you want to search for"
         << " and then press enter:\n";
    cin >> searchUser;
    
    
    for(i = 0; i < 3; i++)
{
if (fname[i] == searchUser)
{
break;
}
}
    
if(i > 9)
{
cout << "\n" << searchUser << " was not found." << endl;
}
else
{
cout << "\n" << searchUser << " was found in the phone book! " << searchUser << "'s number is " 
<< phoneNumber[i] << "." << endl;
}
} 


void print(int i, string lname[3], string fname[3], string phoneNumber[3])
{
    for (i=0; i<=2; i++)
    {
        cout << lname[i] << "'s number is: " << phoneNumber[i] <<endl;
    }
    cout << endl; 
}
How do I stop a endless loop?

You take it out back and break it's knees.


The cause of your problem is that you are asking the user to input a character, but then you try to read an integer. Input fails → all further input fails → loop never ends.

This exposes two problems:
 • mismatch between instructions and expected input
 • invalid input can break your program

Personally, I have come to always recommend getting all input from the user as a string, then testing the string for validity. This makes it impossible for standard input to fail due to bad input, and heartily encourages you to actively select valid inputs.

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std::string user_input;
bool done = false;

while (!done)
{
  menu();

  getline( std::cin, user_input );
  if (user_input.size())
    switch (std::tolower( user_input[ 1 ] ))
    {
      case 'a': ...;
      ...

      case 'f': done = true; break;

      default: ;
    }

}
std::cout << "Goodbye\n";

Hope this helps.
Last edited on
Fixed my loop issue. But now my arrays will not work correctly. I took it from an old project where it worked perfectly but now outputs 3 blank lines and I can only populate one of those line. Suggestions?
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#include <iostream>
#include <string>
#include <cctype>

char menu() // return the selection made by the user
{
    std::cout << "\nWelcome to your Contact Manager. Please select an option\n"
              << "a. Input Data\n"
              << "b. Sort Data Ascending\n"
              << "c. Sort Data Descending\n"
              << "d. Print All Data\n"
              << "e. Search for an individual in the data\n"
              << "f. End Program\n" ;

    char choice ;
    std::cout << "enter your choice: " ;
    std::cin >> choice ;
    choice = std::tolower(choice) ; // if upper case, convert to lower case

    static std::string valid_choices = "abcdef" ;

    // if it is a valid choice, return it
    if( valid_choices.find(choice) != std::string::npos ) return choice ;

    std::cout << "invalid choice. try again\n" ;
    return menu() ; // try again
}

const std::size_t ARRAY_SZ = 3 ;

void input( std::string fname[ARRAY_SZ], std::string lname[ARRAY_SZ], std::string phone[ARRAY_SZ] )
{
    for( std::size_t i = 0 ; i < ARRAY_SZ ; ++i )
    {
        std::cout << "Enter Person's first name: " ;
        std::cin >> fname[i] ;

        std::cout << "Enter Person's last name: " ;
        std::cin >> lname[i] ;

        std::cout << "Enter Person's phone number: " ;
        std::cin >> phone[i] ;
    }
}

void print( const std::string fname[ARRAY_SZ], const std::string lname[ARRAY_SZ], const std::string phone[ARRAY_SZ] )
{
    for( std::size_t i = 0 ; i < ARRAY_SZ ; ++i )
    {
        std::cout << i+1 << ". " << lname[i] << ", " << fname[i] << ": phone " << phone[i] << '\n' ;
    }
}


int main()
{
    std::string fname[ARRAY_SZ] ;
    std::string lname[ARRAY_SZ] ;
    std::string phone[ARRAY_SZ] ;

    // as long as the choice is not 'f' end program
    for( char selection = menu() ; selection != 'f' ; selection = menu() )
    {
         switch(selection)
         {
             // ...
             case 'a' : input( fname, lname, phone ) ; break ;

             case 'd' : print( fname, lname, phone ) ; break ;

             // etc.
         }
    }
}
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