Practice question · Sort into groups
The operator + adds two numbers but joins two strings. Sort each expression by what it evaluates to.
Groups: Evaluates to a number · Evaluates to a string
- 2 * 5
- 3 + 4
- 10 - 3
- "ab" + "cd"
- "1" + "1"
- "3" + "4"
Hints
- Look at whether the operands are numbers or quoted text before deciding what + does.
- "1" + "1" joins two pieces of text; it does not add two numbers.
Show the answer
Evaluates to a number: 3 + 4, 10 - 3, 2 * 5
Evaluates to a string: "3" + "4", "ab" + "cd", "1" + "1"
Why
With numeric operands + adds; with string operands it concatenates. So "3" + "4" is "34" and "1" + "1" is "11", not 7 or 2. The operator is the same symbol; the operand types decide what it means, mixing them carelessly is a frequent source of bugs.
Practise Variables, Expressions, and Types
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