float calculations

Hello, from a beginner :) :)

I am very new to Arduino and C programming, and trying to find my way through it. Slowly and by reading and trial and error I am learning, so please bear with me...

While I was trying to work with some floats, I noticed that a code such as

float var; var=3/4; Serial.println(var,4);

returns 0.0000

but if you do float var; var=(float) 3/4; Serial.println(var,4);

then it returns 0.7500 (as desired)

Can someone help me understand why is this, and is this (casting) the correct way to use floats?

Much appreciated;

Try var = 3/4.0; to force the calculation to be done as a float rather than integer which is the default.

For integer division, 3/4 is zero, with a remainder of 3.

Wow, that was fast!

thanks for the quick reply

So if I understand this correctly, default calculations happen as int type even though the destination variable is float.

good to know.

Wow, that was fast!

We aim to please !

Unless you tell it differently, the default math operations assume int data types. As Bob pointed out, using a decimal point on numeric constants tells the compiler to use floating point math. As you might guess, all of these forms produce the same result:

void setup() {

float var;


var = 3.0 / 4;

var = 3.0 / 4.0;

var = 3 /(float) 4;

var = (float) 3 / 4;

var = (float) 3 / (float) 4;


void loop() {


They work properly because all of them nudge the compiler in the right direction for the math operation.