error with a while

[gispe]

hi ppl
im back here with a kinda major problem

thing is i made this program for some company that sends letters or packages, and has 3 types of services: to send it the next day with priority, the next day but whithout the priority, or to send it in 2 or more.
the letters must weight 30 gr as max, if its more, then is a package.
packages are also divided: if it weights less than 1000 gr it has a fixed cost, that depends on the day i send it, and if it weights more, i have to add some extra money, also depending on the day.

the problem is when the program just began: i validate if the user wants to start or not. it doesnt take the 0 to go out. if i put the '0', doesnt do anything, and gives an error, if i dont, the program keeps going as if the while wasnt there.

in the word attached, is the error that appear.

hope the explanation is helpfull :S

dont know what it is :S

// cartas_y_paquetes.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>

int main(int argc, char* argv[])
{
	using namespace std;

	char empezar;
	char a_enviar, dia;
	float peso;

	int total_dsp_c = 0, costo_dsp_c = 0;
	int total_dsn_c = 0, costo_dsn_c = 0;

	int total_dsp_p = 0, costo_dsp_p = 0;
	int total_dsn_p = 0, costo_dsn_p = 0;
	int total_dos_d_p = 0, costo_dos_d_p = 0;

	int total_dsp_p1000 = 0, costo_dsp_p1000 = 0;
	int total_dsn_p1000 = 0, costo_dsn_p1000 = 0;
	int total_dos_d_p1000 = 0, costo_dos_d_p1000 = 0;

	int totales_dsp, totales_dsn, totales_dos_d;
	int recaudado_dsp, recaudado_dsn, recaudado_dos_d;
	
	int entregas_totales, costo_total;

	int porc_dsp, porc_dsn, porc_dos_d;

	cout << " Empezar?? " << "\n";         // TO START
	cout << "    1 - SI" << "\n";
	cout << "    0 - NO" << "\n";
	cin >> empezar;
	cout << "\n" << "\n";

	while (empezar != '0')      // IF I PUT THIS WITH '' DOESNT WORK. IF DONT, DOESNT TAKE IT
	{
		cout << " Ingrese lo que va a enviar: " << "\n";
		cout << "    3 - Carta" << "\n";
		cout << "    4 - Paquete " << "\n";
		cin >> a_enviar;
		cout << "\n" << "\n";
		
		cout << " Ingrese dia a enviar: " << "\n";
		cout << "    6 - Dia Siguiente prioritario" << "\n";
		cout << "    7 - Dia siguiente normal" << "\n";
		cout << "    8 - Dos dias o mas" << "\n";
		cin >> dia;
		cout << "\n" << "\n";

		cout << " Ingrese peso del paquete: " << "\n";
		cin >> peso;
		cout << "\n" << "\n";


		if (a_enviar == '3')     
		{
			if(dia == '7')
			{
				costo_dsp_c += 8;
				total_dsp_c += 1;
			}
			else if (dia == '8')
			{
				costo_dsn_c += 5;
				total_dsn_c += 1;
			}
			else if (dia == '9')
				cout << " NO DISPONIBLE" << "\n";
		}
		if ((a_enviar == '4') && (peso <= 1000))
		{
			if (dia == '6')
			{
				costo_dsp_p += 25;
				total_dsp_p +=1;
			}
			else if (dia == '7')
			{
				costo_dsn_p += 20;
				total_dsn_p +=1;
			}
			else if (dia == '8')
			{
				costo_dos_d_p += 15;
				total_dos_d_p +=1;
			}
		}
		if ((a_enviar == '4') && (peso > 1000))
		{
			if (dia == '6')
			{
				costo_dsp_p1000 += 25 + (((peso-1000)/500)+2);
				total_dsp_p1000 +=1;
			}
			else if (dia == '7')
			{
				costo_dsn_p1000 += 20 + (((peso-1000)/500)+1.5);
				total_dsn_p1000 +=1;
			}
			else if (dia == '8')
			{
				costo_dos_d_p1000 += 15 + (((peso-1000)/500)+1);
				total_dos_d_p1000 +=1;
			}
		}

		cout << " Seguir??" << "\n";
		cout << "    1 - SI" << "\n";
		cout << "    0 - NO" << "\n";
		cin >> empezar;
		cout << "\n" << "\n";
	}


// CALCULATE TOTALS

	totales_dsp = total_dsp_c + total_dsp_p + total_dsp_p1000;
	totales_dsn = total_dsn_c + total_dsn_p + total_dsn_p1000;
	totales_dos_d = total_dos_d_p + total_dos_d_p1000;

	entregas_totales = totales_dsp + totales_dsn + totales_dos_d;

	recaudado_dsp = costo_dsp_c + costo_dsp_p + costo_dsp_p1000;
	recaudado_dsn = costo_dsn_c + costo_dsn_p + costo_dsn_p1000;
	recaudado_dos_d = costo_dos_d_p + costo_dos_d_p1000;

	costo_total = recaudado_dsp + recaudado_dsn + recaudado_dos_d;

	porc_dsp = (totales_dsp * 100) / entregas_totales;
	porc_dsn = (totales_dsn * 100) / entregas_totales;
	porc_dos_d = (totales_dos_d * 100) / entregas_totales;



// SHOW ALL TOTALS

	cout << "         ---         " << "\n";
	cout << "         ---         " << "\n";
	cout << "                     " << "\n";
	cout << " Las entregas totales hechas al dia siguiente prioritario fueron: " << totales_dsp << "\n";
	cout << " Las entregas hechas al dia siguiente normal fueron:" << recaudado_dsn << "\n";
	cout << " Las entregas realizadas a los dos dias o mas son: " << totales_dos_d << "\n";
	cout << "                     " << "\n";
	cout << "         ---         " << "\n";
	cout << "                     " << "\n";
	cout << " Lo recaudado en el dia siguiente prioritario es de " << recaudado_dsp << "\n";
	cout << " Lo que se recaudo por enviar en el dia siguiente normal fue de " << recaudado_dsn << "\n";
	cout << " Lo recaudado a los dos dias o mas fue de " << recaudado_dos_d << "\n";
	cout << "                     " << "\n";
	cout << "         ---         " << "\n";
	cout << "                     " << "\n";
	cout << " El porcentaje de las ventas del dia siguiente prioritario es de " << porc_dsp << "\n";
	cout << " El porcentaje de las ventas del dia siguiente normal es de " << porc_dsn << "\n";
	cout << " El porcentaje de las ventas de  dos dias o mas es de " << porc_dos_d << "\n";
	cout << "                     " << "\n";
	cout << "         ---         " << "\n";
	cout << "         ---         " << "\n";



	system ("PAUSE");
	return 0;
}

[vmanes]

That error message is one of the clearest there is.

The problem is, if the user immediately chooses NO ( '0' ), you skip the while loop and go on to the summary calculations. entregas_totales gets set to value zero, and is used as a divisor a little bit further on. Integer division by zero is mathematically undefined, and causes a hardware abort of your program.

I think the simple solution is to place a transaction counter inside the loop - keep track of how many times you've processed, or just a boolean variable to know that you have entered the loop at least once. Test that that with an if( ) statement before doing the summary calculations.

[WaltP]

Second problem is you are forgetting that the RETURN you type in is also a character that gets put into the buffer. Therefore, in this code:

cout << " Empezar?? " << "\n";         // TO START
	cout << "    1 - SI" << "\n";
	cout << "    0 - NO" << "\n";
	cin >> empezar;
	cout << "\n" << "\n";

	while (empezar != '0')      // IF I PUT THIS WITH '' DOESNT WORK. IF DONT, DOESNT TAKE IT
	{
		cout << " Ingrese lo que va a enviar: " << "\n";
		cout << "    3 - Carta" << "\n";
		cout << "    4 - Paquete " << "\n";
		cin >> a_enviar;
		cout << "\n" << "\n";

if you enter 0, empezar gets the value '0'
if you enter 1, empezar gets the value '1' and a_enviar reads the RETURN.
if you enter only RETURN, empezar reads the RETURN and since it's not '0' the loop is started.

[vmanes]

if you enter only RETURN, empezar reads the RETURN and since it's not '0' the loop is started.

On what system? cin >> x; skips whitespace, grabs a character(s) then halts at any whitespace. If it's not gotten a character, the program just sits waiting.

Now, using cin.get( ) is a whole 'nuther story.

[WaltP]

Ahhh, yes. Thanks for the correction, vmanes. I was thinking of another input style. Had a brain fart... :icon_redface:

[gispe]

hi ppl, ive just changed the 0 for a 2, but it brings the exact same error.

and it points to the

porc_dsp = (totales_dsp * 100) / entregas_totales;
	porc_dsn = (totales_dsn * 100) / entregas_totales;
	porc_dos_d = (totales_dos_d * 100) / entregas_totales;

i just thought that those lines "are where they're supoused to be", cuz theyre calculating the percentage of what i entered before. so, they should be outside the while i use to validate if i begin or not.
but, maybe, it just doesnt take it, n should be in the while. but this is illogical, cuz i would be calculating it all day long and has no sens. it should be done just once, after receiving all data.

what would my problem be??

[vmanes]

Since it's possible that no transactions occurred, this block must be defended against division by zero, as in:

if( entregas_totales != 0 )  //it's ok to do this
{
	porc_dsp = (totales_dsp * 100) / entregas_totales;
	porc_dsn = (totales_dsn * 100) / entregas_totales;
	porc_dos_d = (totales_dos_d * 100) / entregas_totales;
}
else
{ 
   //handle the error
}

Any time you have division by an integer variable, and you cannot absolutely, positively be certain it can NEVER hold value zero, you should set up such a test.