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how to validate numeric input only using cin

Jan 30, 2013 at 8:19am
Josh Henry (59)
So I am having trouble with this program it works but I need to input 2 values from the same line separated by a space using cin double chevrons!? I cannot use stringstream have to use some form of a char* token[] function using atof without having the program skip the second input if a non numeric is entered such as ten instead of 10, also need to have input read as a floating point or double int?! please correct or help me this is the code I have
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#include <iostream>
using std::cout;
using std::cin;
using std::endl;
using std::ios;

#include <iomanip>
using std::setprecision;

int main()
{
// Beginning information on lab and programmer

  cout << endl;
  cout << "Lab: 2" << endl;
  cout << "Programmer: Joshua Henry" << endl;
  cout << endl;

// Declare variables for cost, pay and change as well as double int
// for declaring change total with decimal point

  double pur = 0;
  double tend = 0;
  int change = 0;
  double balAmt = 0.0;

// constants to define amount for each bill and coin
  const int FIFTY = 5000;
  const int TWENTY = 2000;
  const int TEN = 1000;
  const int FIVE = 500;
  const int ONE = 100;
  const int FIFTYCENT = 50;
  const int QUARTER = 25;
  const int DIME = 10;
  const int NICKEL = 5;
  const int PENNY = 1;

// ints for the amount of bills in change  
  int fiftyBill = 0;
  int twentyBill = 0;
  int tenBill = 0;
  int fiveBill = 0;
  int oneBill = 0;
  int fiftyCent = 0;
  int quarterCent = 0;
  int dimeCent = 0;
  int nickelCent = 0;
  int pennyCent = 0;

// Ask the user to input both purchase and tendered amount

  cout << "Please enter the Purchase amount and amount tendered(seperated by a space): \n";
  cin >> pur >> tend;
  cin.ignore(0, ' ');

// converts purchase amount and tendered into int to solve  
  int cost = pur * 100;
  int pay = tend * 100;
 
// make operations to determine how many bills the change entitles
  change = pay - cost;
 
// while loop to get exact change in bills and coins till change due is zero
  while (change > 0)
  {
    if (change >= 5000)
    { 
      fiftyBill = change / FIFTY;
      change = change - (FIFTY * fiftyBill); 
    } 
      else if (change >= 2000)
      {
        twentyBill = change / TWENTY;
        change = change - (TWENTY * twentyBill);
      }
      else if (change >= 1000)
      {
        tenBill = change / TEN;
        change = change - (TEN * tenBill);
      }
      else if (change >= 500)
      { 
        fiveBill = change / FIVE;
   	change = change - (FIVE * fiveBill);
      }
      else if (change >= 100)
      {
	oneBill = change / ONE;
	change = change - (ONE * oneBill);
      }
      else if (change >= 50)
      {
	fiftyCent = change / FIFTYCENT;
 	change = change - (FIFTYCENT * fiftyCent);
      }
      else if (change >= 25)
      {
	quarterCent = change / QUARTER;
 	change = change - (QUARTER * quarterCent);
      }
      else if (change >= 10)
      { 
	dimeCent = change / DIME;
 	change = change - (DIME * dimeCent);
      }
      else if (change >= 5)
      { 
	nickelCent = change / NICKEL;
    	change = change - (NICKEL * nickelCent);
      }
      else if (change >= 1)
      {
 	pennyCent = change / PENNY;
	change = change - (PENNY * pennyCent);
      }
    
    }

// calculates the amount due with setprecision and showpoint

  balAmt = tend - pur;
  cout.setf(ios::fixed|ios::showpoint);
  cout << setprecision(2);
  cout << endl;

// output the amount of purchase, tendered and change due  
  cout << "For a purchase of " << pur << " the amount tendered is " << tend << endl;
  cout << "Your change will be $" << balAmt << endl;
  cout << endl;

// if statements to determine whether or not to output bill and coin values
  if (fiftyBill != 0 && fiftyBill == 1)
    cout << fiftyBill << " $50 bill" << endl;
  if (fiftyBill > 1)
    cout << fiftyBill << " $50 bills" << endl;
  
  if (twentyBill != 0 && twentyBill == 1)
    cout << twentyBill << " $20 bill" << endl;
  if (twentyBill > 1)
    cout << twentyBill << " $20 bills" << endl;

  if (tenBill != 0 && tenBill == 1)
    cout << tenBill << " $10 bill" << endl;
  if (tenBill > 1)
    cout << tenBill << " $10 bills" << endl;

  if (fiveBill != 0 && fiveBill == 1)
    cout << fiveBill << " $5 bill" << endl;
  if (fiveBill > 1)
    cout << fiveBill << " $5 bills" << endl;

  if (oneBill != 0 && oneBill == 1)
    cout << oneBill << " $1 bill" << endl;
  if (oneBill > 1)
    cout << oneBill << " $1 bills" << endl;

  if (fiftyCent != 0 && fiftyCent == 1)
    cout << fiftyCent << " 50-cent coin" << endl;
  if (fiftyCent > 1)
    cout << fiftyCent << " 50-cent coins" << endl;

  if (quarterCent != 0 && quarterCent == 1)
    cout << quarterCent << " 25-cent coin" << endl;
  if (quarterCent > 1)
    cout << quarterCent << " 25-cent coins" << endl;

  if (dimeCent != 0 && dimeCent == 1)
    cout << dimeCent << " 10-cent coin" << endl;
  if (dimeCent > 1)
    cout << dimeCent << " 10-cent coins" << endl;

  if (nickelCent != 0 && nickelCent ==1)
    cout << nickelCent << " 5-cent coin" << endl;
  if (nickelCent > 1)
    cout << nickelCent << " 5-cent coins" << endl;

  if (pennyCent != 0 && pennyCent == 1) 
    cout << pennyCent << " 1-cent coin" << endl;
  if (pennyCent > 1)
    cout << pennyCent << " 1-cent coins" << endl;
   
    cout << endl;

}
Edit & run on cpp.sh
Last edited on Jan 30, 2013 at 8:38am
Jan 30, 2013 at 12:10pm
Chervil (7320)
I need to input 2 values from the same line
I cannot use stringstream have to use some form of a char* token[] function using atof

That sounds a bit like a reference to strtok()
http://www.cplusplus.com/reference/cstring/strtok/

There are several ways to tackle this. One is to get the entire line as a single character string, and then parse it to get the two numbers. Another would be to get the two parts as two separate strings, as here:
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#include <iostream>
using std::cout;
using std::cin;
using std::endl;
using std::ios;

#include <iomanip>
using std::setprecision;

#include <cstdlib>

int main()
{
// Declare variables for cost, pay and change as well as double int
// for declaring change total with decimal point

  double pur = 0;
  double tend = 0;


  char cpur[50];
  char ctend[50];

// Ask the user to input both purchase and tendered amount

  cout << "Please enter the Purchase amount and amount tendered(separated by a space): \n";
  cin >> cpur >> ctend;

  pur = atof(cpur);
  tend = atof(ctend);

// display the input as a string, them as a number

    cout << "cpur  = " << cpur << endl;
    cout << "ctend = " << ctend << endl;
    cout << "\n---------------------\n\n";

    cout << "pur  = " << pur << endl;
    cout << "tend = " << tend << endl;

    return 0;
}
Edit & run on cpp.sh


Normally I'd use the C++ std::string for this purpose, not sure whether that is allowed here.

Jan 30, 2013 at 9:21pm
Josh Henry (59)
ya I used that but he said he wanted the double chevron usage in this program very anal and not letting me get credit till I do it the "way" he taught in class but thanks Ill try and that
Jan 30, 2013 at 9:26pm
Josh Henry (59)
Chervil your the man! or woman! appreciate it hopefully it will pass inspection this time!
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