//TangYatHo230087110
// Program: Q1_Extend_Ex5_Array.ino
/*
Q1 Extend the program Ex5_Array to read an integer (with at most 2 digits) from 
the Serial Monitor and print out a group of stars that is equal to the integer
value. The stars should be arranged in rows of ten.
For example:
This is a test
Incorrect input
5234
Incorrect input
72
**********
**********
**********
**********
**********
**********
**********
**
0
8
********
*/


char buf[100] = {0};     // this is an array
char inChar; // this is a variable to store the current character read from the Serial Monitor 
bool stringComplete = false;// this is a flag to indicate whether the input string is complete
int i = 0;//// this is a counter to keep track of the array index
bool goodString;//// this is a flag to indicate whether the input string is a valid integer 
int Num;// this is a variable to store the converted integer value

// declare the function
//char ConvertString(char);
void PrintStars(int);// this is a function to print stars according to the integer value

void setup()//runs once when the program starts and is used to initialize the Serial communication.
{
  // Initialize serial and wait for port to open
  Serial.begin(115200);// this is a function to set the data rate in bits per second for serial data transmission 
  while (!Serial)// this is a loop to wait until the serial port is ready 
  {
  }
}

void loop()//runs repeatedly and is used to read the input from the Serial Monitor 
{
  while (Serial.available()) // this is a loop to check if there is any data available on the serial port 
  {
    inChar = (char)Serial.read(); // this is a function to read the incoming serial data as a character and assign it to the variable inChar
      if (inChar == '\n')   // this is a condition to check if the character is a newline character, which indicates the end of the input string
      {
        buf[i++] = inChar;  // this is a statement to append the newline character to the array
        buf[i] = 0;          // this is a statement to add a null terminator to the array, which indicates the end of the string
        stringComplete = true; // this is a statement to set the flag to true, which indicates the input string is complete
      }
      else                  // this is a condition to handle other characters
      {

        buf[i++] = inChar;  // this is a statement to append the character to the array
      }
  }

  if (stringComplete)// this is a condition to check if the input string is complete
  {
    goodString = true;// this is a statement to assume the input string is a valid integer

    if (!(isdigit(buf[0]) && ((i == 2) || ((i == 3) && (isdigit(buf[1])))))) {// this is a condition to check if the input string is not a valid integer, which means it is not a single digit or a two-digit number
      goodString = false;// this is a statement to set the flag to false, which indicates the input string is not a valid integer
    }

    if (goodString) // this is a condition to check if the input string is a valid integer
    {
      if (i == 2)// this is a condition to check if the input string is a single digit
      {
        Num = buf[0] - '0';// this is a statement to convert the character to an integer by subtracting the ASCII value of '0'
      }
      else // this is a condition to handle a two-digit number
      {
        Num = (buf[0] - '0') * 10 + (buf[1] - '0');// this is a statement to convert the two characters to an integer by multiplying the first one by 10 and adding the second one, after subtracting the ASCII value of '0'
      }
      Serial.println(Num);// this is a function to print the integer value to the Serial Monitor, followed by a newline
      PrintStars(Num);// this is a function call to print stars according to the integer value
    }
    else // this is a condition to handle an invalid input string
    {
      Serial.print(buf);// this is a function to print the input string to the Serial Monitor
      Serial.println("Incorrect input");// this is a function to print an error message to the Serial Monitor, followed by a newline
    }

    stringComplete = false;// this is a statement to reset the flag to false, which indicates the input string is not complete
    i = 0; // this is a statement to reset the counter to zero, which indicates the array index is at the beginning
    //Serial.println();
  }
}

// body of the function
/*
  char ConvertString(char x)
  {
  if (isUpperCase(x))
    return (toLowerCase(x));
  else if (isLowerCase(x))
    return (toUpperCase(x));
  else
    return (x);
  }
*/

void PrintStars(int n)// this is a function definition to print stars according to the integer value
{
  for (int i = 1; i <= n; i++) // this is a loop to iterate from 1 to n, where n is the integer value 
  {
    Serial.print("*");// this is a function to print a star to the Serial Monitor
    if (!(i % 10))// this is a condition to check if i is divisible by 10, which means a row of 10 stars is completed 
      Serial.println(); // this is a function to print a newline to the Serial Monitor 
  }
  if (n % 10)// this is a condition to check if n is not divisible by 10, which means the last row of stars is incomplete
    Serial.println(); // this is a function to print a newline to the Serial Monitor return; // this is a statement to return from the function
  return;
}