What is the difference between lvalue and rvalue?

Question

Accepted Answer

**lvalue** — has identity, can appear on left side. **rvalue** — temporary, no identity.

**lvalue:**
- Has name and address.
- Can be modified.
- Persists beyond expression.

```cpp
int x = 10;     // x is lvalue
int& ref = x;   // ref is lvalue
int* ptr = &x;  // OK — has address
```

**rvalue:**
- Temporary, no name.
- Cannot be modified.
- Destroyed after expression.

```cpp
int x = 10;        // 10 is rvalue
int y = x + 5;     // x + 5 is rvalue
std::string("hi");  // rvalue
```

**C++11 extended values:**

**xvalue (expiring value):**
- About to be moved.
- `std::move(x)` returns xvalue.

**glvalue (generalized lvalue):**
- Either lvalue or xvalue.

**prvalue (pure rvalue):**
- Not xvalue (literal, temporary).

**Reference types:**
- `int&` — lvalue reference.
- `int&&` — rvalue reference (C++11).

C++: What is the difference between lvalue and rvalue?