#include <stdio.h>
#include <stdlib.h>
#include <locale.h>

main()
{
      setlocale (LC_ALL, "rus");

      int number_account = 0;
      float start_balance, TotalCost, TotalCredit, ExtendOfCredit, NewBalance, Balance;

      while (number_account != -1)
      {
         printf("Number account - ");
         scanf("%d", &number_account);
         printf("start_balance: ");
         scanf("%f", &start_balance);
         printf("TotalCost: ");
         scanf("%f", &TotalCost);
         printf("TotalCredit: ");
         scanf("%f", &TotalCredit);
         printf("ExtendOfCredit: ");
         scanf("%d", &ExtendOfCredit);
         NewBalance = start_balance + TotalCost - TotalCredit;

         if (NewBalance > ExtendOfCredit)
         {
            printf("number_account: %d", number_account);
            printf("ExtendOfCredit: %.2f", ExtendOfCredit);
            printf("Balance: %.2fn n", Balance = start_balance + TotalCredit);
         }
      }
      system("PAUSE");
}

#include <stdio.h>
#include <stdlib.h>

// прочтем все символы до новой строки
// вернем (для любопытных) их количество
// или EOF (для анализа конца файла (это уже не пустое любопытство))
static int
skip()
{
  int c, n = 0;

  if (!feof(stdin)) // убедимся, что нужно читать
    while ((c = getchar()) != EOF) {
      n++;
      if (c == 'n')
        return n;
    }
  return EOF;
}

int
main ()
{
  int a, b, i = 0, rc;

  while (rc !=  EOF) {
    printf ("Enter a,b: "); fflush(stdout);
    rc = scanf("%d%d",&a,&b);
    printf ("rc = %d  a = %d b = %dn", rc,a,b);
#if ERRDEMO
    if (rc == 2)
      i = 0;
    else if (++i > 5)
      break;
#else
    if (rc != EOF)
      if (rc != 2) {
        printf ("Input error rc = %dn",rc);
        printf ("skip %d charactersnTry again ",rc = skip());
      }
#endif
  }

  exit (0);
}

gcc a.c

gcc -DERRDEMO a.c

avp@avp-xub11:~/hashcode$ gcc a.c -DERRDEMO
avp@avp-xub11:~/hashcode$ ./a.out
Enter a,b: 1 2
rc = 2  a = 1 b = 2
Enter a,b: 3 a
rc = 1  a = 3 b = 2
Enter a,b: rc = 0  a = 3 b = 2
Enter a,b: rc = 0  a = 3 b = 2
Enter a,b: rc = 0  a = 3 b = 2
Enter a,b: rc = 0  a = 3 b = 2
Enter a,b: rc = 0  a = 3 b = 2
avp@avp-xub11:~/hashcode$ gcc a.c
avp@avp-xub11:~/hashcode$ ./a.out
Enter a,b: 1 2
rc = 2  a = 1 b = 2
Enter a,b: 3 a
rc = 1  a = 3 b = 2
Input error rc = 1
skip 2 characters
Try again Enter a,b: 3 4
rc = 2  a = 3 b = 4
Enter a,b: 5 6f
rc = 2  a = 5 b = 6
Enter a,b: rc = 0  a = 5 b = 6
Input error rc = 0
skip 2 characters
Try again Enter a,b: 5 6
rc = 2  a = 5 b = 6
Enter a,b: rc = -1  a = 5 b = 6
avp@avp-xub11:~/hashcode$