printf being duplicated after the first loop

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-2

I have this program and in the first loop of while it runs normally, print one single time each thing, but in the second loop it printa "Type S to vote, N to see the vote count and exit." twice before reading. Can anyone tell me why?

#include "pch.h"
#include <iostream>
#include <locale.h>

int main() {

    char resp;
    int presidente[15], governador[12], votop = 0, votog = 0, i = 0, x=2;



    while (x != 0) {

        printf ("Digite S para votar, N para ver a apuracao dos votos e sair. ");
        fflush(stdin);
        resp = getchar();

        if (resp == 's' || resp == 'S') {

            printf("\n\n\n Digite o numero para presidente: ");
            fflush(stdin);
            scanf_s("%d", &votop);

            i = votop;

            presidente[i] = presidente[i] + 1;

            printf("\n\nAgora digite o numero para gorvernador: ");
            fflush(stdin);
            scanf_s("%d", &votog);

            i = votog;

            governador[i] = governador[i] + 1;

            printf("\n\n\nObrigado por votar.\n\n\n");

        }
        if (resp == 'n' || resp == 'N') {
            x = 0;
        }
    }




    printf("\n\n\n");
    system("pause");
    return 0;
}
c

  • I could not reproduce the error, but I had to change a few things to test on the ideone that does not accept C11, and I took advantage and improved several things to make the code more readable: https://ideone.com/f3RzXt

  • The only modification I noticed regarding the problem was a char before the variable name in getchar, even adding the same error still occurs.

  • No, I just put it somewhere else and showed that the mistake doesn’t happen.

1 answer

-1

C data entry with scanf is a confusing subject. The use of fflush(stdin) is controversial, it doesn’t always work the way we expect. When reading a character, instead of using getchar it is more guaranteed to use scanf(" %c", &ch);, which ensures that the newline character (corresponds to the ENTER or RETURN of the keyboard) is ignored.

Below is a version of the program that works correctly, tested on Linux and Windows.

#include <stdio.h>

int main()
{
  char resp;
  int presidente[15], governador[12], votop = 0, votog = 0, i = 0, x=2;

  while (x != 0)
  {
    printf ("\n");
    printf ("Digite S para votar, N para ver a apuracao dos votos e sair: ");
    scanf(" %c", &resp); // <--- veja o espaço antes do %c

    if (resp == 's' || resp == 'S')
    {
      printf("\nDigite o numero para presidente: ");
      scanf("%d", &votop);

      i = votop;

      presidente[i] = presidente[i] + 1;

      printf("\nAgora digite o numero para gorvernador: ");
      scanf("%d", &votog);

      i = votog;

      governador[i] = governador[i] + 1;

      printf("\nObrigado por votar\n");
    }

    if (resp == 'n' || resp == 'N')
    {
      x = 0;
    }
  }

}

ADDENDUM:

Test on Windows 10, compiled with Visual Studio 2005

D:\projects\misc
$ so339544.exe

Digite S para votar, N para ver a apuracao dos votos e sair: X

Digite S para votar, N para ver a apuracao dos votos e sair: X

Digite S para votar, N para ver a apuracao dos votos e sair: X

Digite S para votar, N para ver a apuracao dos votos e sair: N

D:\projects\misc
$ so339544.exe

Digite S para votar, N para ver a apuracao dos votos e sair: s

Digite o numero para presidente: 13

Agora digite o numero para gorvernador: 40

Obrigado por votar

Digite S para votar, N para ver a apuracao dos votos e sair: n

D:\projects\misc
$

  • Thanks for the help, but when I use the scanf the way the program told me It totally uga and begins to descend letters infinitely on the screen.

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