Variables and Data Types

A variable is a name given to a place in memory where a value is stored. In Python, a value is given to a variable with the equals sign: age = 15. This is not an equation from mathematics but a command meaning “store the value on the right under the name on the left”, so the line age = age + 1 increases the value of the variable by 1.

A variable name starts with a letter or an underscore (_), and it may contain letters, digits and _; spaces are not allowed. Names are case-sensitive: age and Age are two different variables. Python keywords such as if and for cannot be used as names.

The main data types are the whole number int (for example, 15), the decimal number float (3.14), the text str ("Ali") and the logical value bool (True or False). The type() function finds out the type of a value. The input() function always returns text, so if you need a number, convert the result like this: int(input("Yoshingiz: ")).

The operations +, -, * and / work on numbers. In addition, // means whole-number division, % gives the remainder of a division, and ** raises to a power: the result of 7 // 2 is 3, of 7 % 2 is 1, and of 2 ** 3 is 8. Ordinary division always gives a decimal number: the result of 7 / 2 is 3.5.

Key takeaways

• A variable is a named place in memory for a value; the value is set with the = sign.
• A name starts with a letter or _, and uppercase and lowercase letters are different.
• The main types are int, float, str and bool.
• input() returns text; to get a number, convert it with int() or float().
• Numbers support +, -, *, /, as well as whole-number division // and remainder %.