Types

Arithmetic Types (Size, Range, Type Specifier)

Variable

• Declare variable

// [type] [variable name];
int age; // declares an integer variable named 'age'
float weight; // declares a float variable named 'weight'
char firstLetter; // declares a character variable named 'firstLetter'

• Once declared, you can assign values to these variables like this:

age = 20; // assigns the value 20 to 'age'
weight = 70.5; // assigns the value 70.5 to 'weight'
firstLetter = 'A'; // assigns the character A to 'firstLetter'

• You can also declare and assign values at the same time:

int age = 20;
float weight = 70.5;
char firstLetter = 'A';

• You may group the identifiers of variables that share the same type within a single declaration by separating the identifiers by commas.

 char   children, digit;
 int    nPages = 10, nBooks = 3, nRooms = 1;
 float  cashFare, height = 185.5, weight = 70.5;
 double loan, mortgage;

• You can use const keyword to declare a constant. A constant is a type of variable whose value cannot be changed after it's been defined.

const int myConstant = 10;

Naming Conventions

• Start with a letter or an underscore (_).
• Use any mix of letters, numbers, and underscores (_).
• Keep it under 32 characters long.
• Don't use C reserved words

Tips for good variable names

• Make the name explain what it's used for.
• Keep it short but clear.
• Make sure the name matches what data is stored in it.
• The name should make your code easier to read.
• Use "camelNotation" where the first letter of each word is capitalized except the first word (like "myVariableName").
• Avoid using underscores (_) because system libraries often use them and you don't want to mix up your variables with theirs.