Calculating Percent Values

Using Arduino Programming Questions
1

So I tried to get the percent value from a byte (val2) with this code:

int val1;     //output value
byte val2;  //input value

val1 = (val2 / 255) * 100;

Complete Code:

#include <LiquidCrystal.h>

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

int val3;
byte val2;
int val1;

void setup() {
  lcd.begin(16, 2);
}

void loop() {
  val3 = analogRead(A0);
  val2 = val3 / 4;
  val1 = (val2 / 255) * 100;
  
  lcd.setCursor(0, 0);
  lcd.print("I: ");
  lcd.setCursor(3, 0);
  lcd.print(val3);

  lcd.setCursor(9, 0);
  lcd.print("B: ");
  lcd.setCursor(12, 0);
  lcd.print(val2);
  if(val3 <= 999){
    lcd.setCursor(6, 0);
    lcd.print(" ");
  }

  lcd.setCursor(0, 1);
  lcd.print("%: ");
  lcd.setCursor(3, 1);
  lcd.print(val1);
}

and all I get as an output is 0

what did I do wrong?

2

Sv443:
what did I do wrong?

You didn't read the sticky "Read this before posting a programming question"

3

I don't know what you're referring to. Do you mean I have to post the full code? I did that now.

4

Hint: Follow the link I gave

5

You have a byte variable, which can hold a value between 0 and 255. You divide that by 255. What do you expect the result to be?

Regards,
Ray L.

6

Try

int val1;
byte val2 = 128;

void setup() {
  Serial.begin(250000);
  val1 = (val2 / 255.0) * 100;
  Serial.print(val1);
}

void loop() {}

50

7

RayLivingston:
You have a byte variable, which can hold a value between 0 and 255. You divide that by 255. What do you expect the result to be?

I don't actually know. Now that you say it it doesn't make any sense.

I wanted my input value to be for example 150 of 255 which would yield 0.58 , so 58%

8

I am so confused now...
The calculation works just fine on my calculator.
For example if I do (15 / 255) * 100 = 5%
My Arduino just prints a 0

9

Unless forced to do otherwise the calculation will be done with all the values being regarded as integers. Make at least one of the values in the calculation a float and the calculation will be done using floats

See reply #5

10

UKHeliBob:
Unless forced to do otherwise the calculation will be done with all the values being regarded as integers. Make at least one of the values in the calculation a float and the calculation will be done using floats

See reply #5

Thank you very much. I did not know that. Now it works just fine.

11

If you first multiply by 100 and next divide, you will also circumvent the problem.

12

HaecuD:
Hey, so does anyone know if this calculator can give me the correct percentage calculation?

Which calculator?

13

HaecuD:
Hey, so does anyone know if this calculator can give me the correct percentage calculation?

This post looks suspiciously like spam and/or a SEO link