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Programming Fundamentals › Programming Basics

Operator

A symbol that performs an operation on values, like +, == or &&.

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Also known as: operators, symbols in code

An operator is a symbol (or keyword) that performs an operation on values, called operands. +, == and && are all operators.

KindExamples
Arithmetic+ - * / % **
Comparison== != < > <= >=
Logicaland or not (Python), && || ! (JavaScript)
Assignment= += -= *=
Membershipin, not in (Python)
Bitwise& | ^ << >> (bitwise operations)
total = price * qty + shipping      # arithmetic and assignment
ok = age >= 18 and not banned       # comparison and logic
"a" in "cat"                        # True

A unary operator takes one operand (-x, !flag), a binary one takes two (a + b), and the ternary cond ? a : b takes three (ternary operator).

Traps

  • = vs ==. One assigns, the other compares.
  • + means different things for numbers (add) and strings (join), and mixing them can fail or coerce (type coercion).
  • / divides as floats in Python 3 and JavaScript, but as integers in some languages.
  • Chained comparison works as math in Python (1 < x < 10), not in most others.
  • Order of evaluation is set by precedence. When unsure, use parentheses.