Programming Fundamentals › Programming Basics

Integer

A whole-number type, usually with a fixed size and range.

Also known as: int, whole number, signed integer

An integer is a whole number with no fractional part: -3, 0, 42. It’s the type to use for counting and for anything that must be exact, like IDs, quantities and money in cents.

7 // 2      # 3    integer division
7 % 2       # 1    remainder
7 / 2       # 3.5  true division gives a float

Size and range

In many languages an integer has a fixed size in bits, so it has a limited range:

Going past the limit is an overflow. Python integers grow as needed, while JavaScript has only floating-point Number, which is exact for integers up to 2⁵³ − 1 and has BigInt beyond that.

Things to watch

• Integer division. 7 / 2 is 3 in some languages (Java, C) and 3.5 in others (Python 3, JavaScript).
• Negative remainders differ between languages (-7 % 3).
• Exact comparisons. Unlike floats, integers compare reliably (floating point).
• IDs are not for arithmetic. Phone numbers and postal codes look numeric but are better as strings (leading zeros matter).
• Pick a type with room. A 32-bit auto-increment ID runs out at about 2.1 billion rows.

Money should be stored as integers of the smallest unit, or exact decimals (money precision).