& vs. &&: What's the Difference?

Edited by Aimie Carlson || By Janet White || Published on February 11, 2024
& is a bitwise operator; && is a logical AND operator.

Key Differences

& and && are both used in programming but serve different purposes. & is a bitwise operator. It operates on individual bits of integer data types. For example, in a & b, it compares corresponding bits of a and b and returns a new number with bits set if both bits in the same position in a and b are set.
&& is a logical AND operator used in conditional statements. It evaluates to true only if both operands are true. Unlike &, && operates at a higher level, working with boolean values rather than bits. In a && b, if a is false, b is not evaluated, showcasing short-circuit behavior.
& can also be used in logical operations in some languages, but without short-circuiting. If a & b is used logically, both a and b are evaluated even if a is false, differing from && in its execution.
&& is primarily found in high-level languages like Java, C++, and JavaScript for control flow in conditional statements. Its functionality is crucial for decision-making processes in programs, allowing for complex conditions.
&, apart from its bitwise use, is sometimes seen in older code or specific contexts where bitwise operations are necessary. It is less common in everyday programming compared to &&, which is integral to most conditional logic in programming.

Comparison Chart

Type

Bitwise operator
Logical AND operator

Bit-level
Boolean level

Short-Circuit Behavior

Does not short-circuit
Short-circuits (second operand is not evaluated if the first is false)

Usage

In bitwise operations
In logical expressions, primarily in conditional statements

Evaluation

Both operands always evaluated
Second operand evaluated only if the first is true

& and && Definitions

&

Used as a symbol for 'and' in informal contexts.
Peanut butter & jelly sandwiches are delicious.

&&

Used in controlling program flow.
If (isLoggedIn && isAuthorized) { // access granted }

&

Combines bits of two numbers.
12 & 5 results in 4.

&&

Operates at boolean, not bit, level.
True && false results in false.

&

Represents the word 'and' in titles and names.
Johnson & Johnson is a well-known company.

&&

Returns true if both operands are true.
If (age > 18 && hasLicense) { // can drive }

&

Originally a ligature of 'e' and 't', the Latin word for 'and.'
The & originated from the Latin 'et'.

&&

Stops evaluating if the first operand is false.
If (false && someFunction()) { // someFunction is not called }

&

In some languages, evaluates both operands logically.
True & false results in false.

&&

Widely used in languages like C++, Java, JavaScript.
If (isRaining && isWeekend) { // stay indoors }

FAQs

Does && exhibit short-circuit behavior?

Yes, if the first operand is false, the second operand is not evaluated.

How does && work in conditional statements?

&& returns true if both operands are true; it's used for logical conjunction.

Is & common in modern programming?

It's less common than && and typically used in specific contexts like bitwise operations.

Can & be used outside of programming?

Yes, it's often used as a symbol for 'and' in informal writing.

Why is short-circuit behavior important for &&?

It improves efficiency by not evaluating the second operand if not necessary.

Is && suitable for complex conditions?

Yes, it's ideal for evaluating multiple boolean expressions in conditional statements.

Does & have a special meaning in typography?

Yes, it's an ampersand, representing the word 'and.'

Are & and && interchangeable?

No, they serve different purposes and are not interchangeable.

Can & affect performance?

Yes, since it evaluates both operands, it might be less efficient in logical operations.

What is & used for in programming?

& is mainly used as a bitwise AND operator.

Can & be used for logical operations?

Yes, in some languages, but it evaluates both operands regardless of the first operand's value.

Is && used in all programming languages?

&& is common in many high-level languages, but not all.

Can && be part of a compound condition?

Yes, it's often used to combine multiple conditions in a single statement.

What happens if I use & instead of && in a conditional?

You might get unexpected results, as & does not short-circuit and operates on bits.

How does & handle boolean values?

It performs a bitwise AND on the underlying binary representation of the booleans.

Are there languages where & and && are used differently?

Yes, their usage and behavior can vary slightly across different programming languages.

Is & ever used in logical expressions in modern programming?

Rarely, as && is more efficient and clearer for logical expressions.

Is understanding && crucial for programming?

Yes, as it's fundamental for control flow and logical expressions in programming.

Can I use && for bitwise operations?

No, && is strictly a logical AND operator.

Is it common to use & in everyday language?

Yes, as an ampersand in writing, but not in verbal communication.