[SOLVED] How do I merge this two unsigned char into a string

Projects General Guidance
1

hello and good day, I am relatively new to programming and I am here trying to find out why is my output is not as per what I expected below is what my sketch looks like

const int tw1_pin1 = 13;
const int tw1_pin2 = 12;
const int tw1_pin4 = 11;
const int tw1_pin8 = 10;

const int tw2_pin1 = 47;
const int tw2_pin2 = 49;
const int tw2_pin4 = 51;
const int tw2_pin8 = 53;

int tw1_pin_one;
int tw1_pin_two;
int tw1_pin_four;
int tw1_pin_eight;

int tw2_pin_one;
int tw2_pin_two;
int tw2_pin_four;
int tw2_pin_eight;

void setup() {
  pinMode(tw1_pin1, INPUT);
  pinMode(tw1_pin2, INPUT);
  pinMode(tw1_pin4, INPUT);
  pinMode(tw1_pin8, INPUT);

  pinMode(tw2_pin1, INPUT);
  pinMode(tw2_pin2, INPUT);
  pinMode(tw2_pin4, INPUT);
  pinMode(tw2_pin8, INPUT);

  Serial.begin(9600);

}

void loop() {

    tw1_pin_one = digitalRead(tw1_pin1);
    tw1_pin_two = digitalRead(tw1_pin2);
    tw1_pin_four = digitalRead(tw1_pin4);
    tw1_pin_eight = digitalRead(tw1_pin8);


    tw2_pin_one = digitalRead(tw2_pin1);
    tw2_pin_two = digitalRead(tw2_pin2);
    tw2_pin_four = digitalRead(tw2_pin4);
    tw2_pin_eight = digitalRead(tw2_pin8);


   unsigned char thumbwheel1 = 0;
  thumbwheel1 += digitalRead(tw1_pin1);
  thumbwheel1 += 2 * digitalRead(tw1_pin2);
  thumbwheel1 += 4 * digitalRead(tw1_pin4);
  thumbwheel1 += 8 * digitalRead(tw1_pin8);

    if (thumbwheel1 == 1)
    {
     Serial.print("TW1 = 1 ");
    }

    if (thumbwheel1 == 2)
    {
      Serial.print("TW1 = 2 ");
    }

    if (thumbwheel1 == 3)
    {
     Serial.print("TW1 = 2 ");
    }

    if (thumbwheel1 == 4)
    {
      Serial.print("TW1 = 4 ");
    }

    if (thumbwheel1 == 5)
    {
      Serial.print("TW1 = 5 ");
    }

    if (thumbwheel1 == 6)
    {
      Serial.print("TW1 = 6 ");
    }
    
    if (thumbwheel1 == 7)
    {
      Serial.print("TW1 = 7 ");
    }
    if (thumbwheel1 == 8)
    {
      Serial.print("TW1 = 8 ");
    }
    if (thumbwheel1 == 9)
    {
      Serial.print("TW1 = 9 ");
    }
    if (thumbwheel1 == 0)
    {
      Serial.print("TW1 = 0 ");
    }


  unsigned char thumbwheel2 = 0;
  thumbwheel2 += digitalRead(tw2_pin1);
  thumbwheel2 += 2 * digitalRead(tw2_pin2);
  thumbwheel2 += 4 * digitalRead(tw2_pin4);
  thumbwheel2 += 8 * digitalRead(tw2_pin8);
    if (thumbwheel2 == 1)
    {
      Serial.print("TW2 = 1 ");
    }

    if (thumbwheel2 == 2)
    {
      Serial.print("TW2 = 2 ");
    }

    if (thumbwheel2 == 3)
    {
      Serial.print("TW2 = 3 ");
    }

    if (thumbwheel2 == 4)
    {
      Serial.print("TW2 = 4 ");
    }

    if (thumbwheel2 == 5)
    {
      Serial.print("TW2 = 5 ");
    }

    if (thumbwheel2 == 6)
    {
      Serial.print("TW2 = 6 ");
    }
    
    if (thumbwheel2 == 7)
    {
      Serial.print("TW2 = 7 ");
    }
    if (thumbwheel2 == 8)
    {
      Serial.print("TW2 = 8 ");
    }
    if (thumbwheel2 == 9)
    {
      Serial.print("TW2 = 9 ");
    }
    if (thumbwheel2 == 0)
    {
      Serial.print("TW2 = 0 ");
    }

    
unsigned char total = 0;

total = thumbwheel1 + thumbwheel2;

Serial.println("total: " + String(total));
delay(1000);
}

below is what I got when I run the sketch

TW1 = 9 TW2 = 9 total: 18

what I want is

TW1 = 9 TW2 = 9 total: 99

I`m using a thumbwheel that read BCD and trying to merge both to make double digit. Can I know where in the part of my sketch is wrong and how do I fix it.

2

would

total = thumbwheel1*10 + thumbwheel2;

give the required value?

3

wait, it worked!

thank you so much and by the way how do you know how to fix it?

5

have a look at C Operator Precedence and associativity