Convert and pad to two digits << SOLVED>>

Projects Programming
1

I am using a keypad with IR receiver - the value when a key is pressed (0)=0x16.(1)=0xC etc
I wish to pad the input to two places and have it shown as 00, 01 - 99
Can anyone help with the coding please.

2 
    if (value < 10)
      Serial.print('0');  // Add leading zero
    Serial.print(value);
3

Thanks for the quick reply - I am not sure how that would convert and pad value.
could you give me a clearer idea.

if value = 0xC then result= ????

4

it’s Hex representation of …

0123456789ABCDEF …

12

5

@dolittle, the idea is not to change the variable itself, but only add the zero when displaying that value.

This is what johnwasser did, I put both decimal and hexadecimal in there:

void setup() 
{
  Serial.begin( 115200);
}

void loop() 
{
  int key = random( 0, 25);

  // ------------------------------------------------
  // Print as decimal
  // ------------------------------------------------
  // Value is 10 or above ? No leading zero
  // Value is 9 or below ? Add leading zero
  if( key < 10)
  {
    Serial.print( "0");     // Add leading zero
  }
  Serial.print( key, DEC);

  // ------------------------------------------------
  // Print as hexadecimal
  // ------------------------------------------------
  // Value is 0x10 or above ? No leading zero
  // Value is 0x9 or below ? Add leading zero
  Serial.print( "  0x");
  if( key < 0x10)
  {
    Serial.print( "0");
  }
  Serial.print( key, HEX);
  Serial.println();

  delay( 500);
}

Try this sketch in Wokwi:

[ADDED] Updated the sketch in Wokwi. Added the printf() as shown by @groundFungus but made it safer.

6

Using the sprintf() function.

int numberA = 7;
int numberB = 0xc;

void setup()
{
    Serial.begin(115200);
    
    char numAstr[5];
    char numBstr[5];
    
    sprintf(numAstr,"%02d", numberA);
    Serial.print("number A = ");
    Serial.print("0X");
    Serial.println(numAstr);
    
    sprintf(numBstr,"%02X", numberB);
    Serial.print("number B = ");
    Serial.print("0X");
    Serial.println(numBstr);   
}

void loop()
{

}

Output:

number A = 0X07
number B = 0X0C

7

It was not clear that you wanted the result in hexadecimal.

    if (value < 0x10)
      Serial.print('0');  // Add leading zero
    Serial.print(value, HEX);
8

Sorry for not explaining myself better - something along this line: I know its not correct but this is what I am looking for

String doConvert(HEX value) {
  string result ;

  if (value < 0x10)
    result = '0'+ 'what';
  else
    result =' what';

      return result;
}

The return should be two characters 01,02,03,04 etc

9 
String doConvert(int value)
{
  String result ;

  if (value < 0x10)
    result = '0' + String(value, HEX);
  else
    result = String(value, HEX);

  return result;
}
10

perfect - thank you

12

Nice to see you came up with own solution

13

Thanks for pointing that out, seems to be floppy fingers.