Convert to for loops?

Using Arduino Programming Questions
1

So i have this code a 3 by 4 keypad. And i want to change it into a for loop. But i've a hard time understanding how i should do so.

The code is using the buttons 1,2,4 and 5 only.
Just wondering if someone could give a hint as to what i should do!

int col1 = 3;
int col2 = 6;

int row1 = 4;
int row2 = 2;

int reading_row1 = 0; 
int reading_row2 = 0;

int pin1 = 8;
int pin2 = 9;
int pin3 = 10;
int pin4 = 11;

void setup()
{
  Serial.begin(9600);
  pinMode(row1, INPUT_PULLUP); 
  pinMode(col1, OUTPUT);
  pinMode(row2, INPUT_PULLUP);
  pinMode(col2, OUTPUT);


  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  digitalWrite(col1, HIGH);
  digitalWrite(col2, HIGH);
  //digitalWrite(col3, HIGH);
}
void loop()
{



  digitalWrite(col1, HIGH);  
  digitalWrite(col2, LOW);

  reading_row1 = digitalRead(row1); 
  reading_row2 = digitalRead(row2);

  if (reading_row1 == LOW)  
  {
    Serial.println("2");
    digitalWrite(9, LOW); 
    digitalWrite(8, LOW);
    digitalWrite(10, HIGH); 
    digitalWrite(11, LOW);
  }
  else if (reading_row2 == LOW) 
  {
    Serial.println("5");
    digitalWrite(9, HIGH); 
    digitalWrite(8, LOW);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
  }

  digitalWrite(col1, LOW); 
  digitalWrite(col2, HIGH);

  reading_row1 = digitalRead(row1);
  reading_row2 = digitalRead(row2);

  if (reading_row1 == LOW)
  {
    Serial.println("1");
    digitalWrite(9, LOW);
    digitalWrite(8, HIGH);  
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);


  }
  else if (reading_row2 == LOW)
  {
    Serial.println("4");
    digitalWrite(9, LOW);
    digitalWrite(8, LOW);
    digitalWrite(10, LOW);
    digitalWrite(11, HIGH);  
  }
}
2

It is unclear from your post WHY you would want to change it into a FOR loop. It is also unclear WHAT you want to change into a FOR loop. Yet, I will take a stab that you want to change the repeated lines digitalWrite() into a FOR loop, and will answer with that assumption. First, make an array of your pin numbers. Next, make an array of bit masks where each bit is a HIGH or LOW (1 or 0). Next, write a function including the FOR loop that when passed an index to the bit mask array, will iterate over the pin array and bits in the indexed bit mask. See
https://forum.arduino.cc/index.php?topic=573864.msg3909078#msg3909078
or
https://forum.arduino.cc/index.php?topic=568258.msg3872202#msg3872202
where I have example code.

3

You well you are right!!
But i cannot check your links?

4

Lexianlex:
You well you are right!!
But i cannot check your links?

I can't get the links to work, but I have removed the code from the links... They should work now if you copy and paste.

5

I recommend the Keypad library which will do all the work for you:

Sketch->Include Library->Manage Libraries...

Type "Keypad" in the "Filter your search..." box.

Scroll down to:
Keypad by Mark Stanley, Alexander Brevig

Click on it and then click on the "Install" button.