Page 61 - Programming the Photon Getting Started With the Internet of Things

Data Type Memory (bytes) Range

boolean 1 true or false (0 or 1)

char 1 −128 to +128

byte 1 0 to 255

int 2 −32768 to +32767

unsigned int 2 0 to 65536

long 4 2,147,483,648 to 2,147,483,647

unsigned long 4 0 to 4,294,967,295

float 4 −34028235E+38 to +3.4028235E+38

double 4 same as float

Table 3.1 Variable Data Types

Another thing to remember is what happens when your values exceed the limits. This

causes odd things to happen. For example, if you have the byte variable with a value of
255 and you suddenly add a 1 to this value, it returns a zero; similar to this, if you add a 1
to an integer with the maximum value of 32767, it becomes a negative value of −32768.
Usually, you can get away with most of your data types being an integer, so sometimes it’s

best to use this data type by default.

Char

The data type char is a byte that represents an ASCII character. ASCII (American

Standard Code for Information Interchange) is a system from the very early days of
computing used to translate between bytes and characters. A char typically only takes up
1 byte of memory that stores a character value. Single characters are written in single

quotes ‘A’ and multiple characters are written in double quotations “ABC.” In theory, a
char is stored as a number according to the ASCII table (e.g., A is equal to the number 65).
Here is how you create and assign a char variable:

char letter = ‘A’;
char letter = 65;

Both examples of using char are correct.