You would think "numbers would be numbers" in all languages but it truly isn't quite the case. All numbers are internally represented in binary inside the microcontroller/computer but how the programming language provides number support tends to vary from language to language.
Types of Numbers
- Integers
- Floating Point Numbers
- Boolean (true/false)
Often times, you need to know the precision - how big or small the number might be to select the best way to use it in a computer program. This makes using numbers a bit trickier but it is fairly easy to learn.
Arduino
In Arduino, you have the following types of variables:
- int for an integer, a value without a decimal point. typical ranges for an integer are -32,768 to zero to 32,767. Examples are 279, 1001, 0, -23, -990.
- long is a large integer and can be a value from -2,147,483,648 to 2,147,483,647.
- float for floating point numbers (numbers with a decimal point and fractional amount). Examples are 3.1415, -22.2, 0.0, 430000.01. Numbers can be as large as 3 x 10 to the 38th power
- char for a single character. For example, reading serial data may involve a receive function providing a character value when data is received. A character may basically be any symbol on the keyboard (0 to 255).
The types.h library provides a more modern representation of numbers that tend to behave the same on different devices.
An unsigned short integer, uint8_t, is often used by functions, it also ranges from 0 to 255.
Boolean math is generally done with int values. 0 is false and anything that is not zero, such as 1, is true.
Python / CircuitPython
CircuitPython tries to follow the standard Python implementation (often called CPython) as close as possible. Given microcontrollers do not have an operating system, some things are done a bit differently, but these are documented.
Here are the current types in CircuitPython:
- Integers, but not currently long integers
- Floating-Point Numbers.
- Strings
- Boolean
Boolean is an actual type in CircuitPython and can be the values True or False.
Rather than use arrays of characters (null/zero terminated) as Arduino does, CircuitPython has a dedicated Strings type. Note that CircuitPython Strings are NOT null/zero terminated, so use of the length properties is how you work with string length.
Changing the Type of Numbers
In Arduino/C this is called casting. Place the type of the number you want in parenthesis before the variable.
int a; float b; b = (float)a; a = (int)b;
In CircuitPython, you use function-like syntax:
x = 5 y = 3.14 z = float(x) z = int(y)
A single forward slash / is floating point division in both languages.
A double slash // in Python is special. It divides and drops any values past the decimal point, often called a floor function.
Example:
# Python code for / and // operators
x = 15
y = 4
# Output: x / y = 3.75
print('x / y =', x/y)
# Output: x // y = 3
print('x // y =', x//y)
Logical Operators
Logical operators are used mainly in if statements and other block / loop statements. These are NOT the operators used for bitwise and/or/not, only for constructing logical comparisons.
|
AND OR NOT
|
Arduino / C && || ! |
Python / CircuitPython and or not |
// Arduino / C Logical Operators
a = 5;
b = 7;
if( a > 2 && b < 10) {
Serial.println("Success");
}
# CircuitPython Logical Operators
a = 5
b = 7
if a > 2 and b < 10:
print("Success")