Variables and Data Types

A variable gives a name to a value stored in memory so you can read or change it later.

Common data types:

• Integer — whole numbers (42, -7).
• Floating point — numbers with fractions (3.14). Stored approximately, so 0.1 + 0.2 is not exactly 0.3.
• Boolean — true / false.
• Character / string — text.

Languages are either statically typed (C, C++, Java — types are checked before running) or dynamically typed (Python — types are checked while running).

int count = 10;        // C: the type is declared
float voltage = 3.3f;

count = 10             # Python: the type comes from the value
voltage = 3.3