String appends the previous input

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>
#include <tvplib.h> //my  header locates string_check() function

int main()
{
char str1[11], str2[11], str3[5];
int i;

  printf("Enter first string: ");
  fgets(str1, 11, stdin);
  for (i=0; i<11; i++)
  if (str1[i]=='\n')
  {
      str1[i]='\0';
      break;
  }
  printf("String 1: %s  Length: %d\n", str1, strlen(str1));

  printf("Enter second string: ");
  fgets(str2, 11, stdin);
  for (i=0; i<11; i++)
  if (str2[i]=='\n')
  {
      str2[i]='\0';
      break;
  }
  printf("String 2: %s  Length: %d\n", str2, strlen(str2));

  printf("Result: %d\n",strcmp(str1,str2));
  printf("Enter password from keyboard: ");
  i=0;
  str3[i]='\0';
  while ((i<4) && (str3[i]!='\n'))
  {
        str3[i]=getch();
        if (str3[i]== '\n')
        {
            break;
        }
        puts("*");
        i++;
  };
  printf("String str3 value: %s\n", str3);
  if (string_check(str3) == 0)
  {
      printf("Correct Password: %s", str3);
  }
  else printf("Wrong Password: %s", str3);

  getch();
  return 0;
}