C++ provides compound assignment operators that combine an arithmetic or bitwise operation with an assignment operation. They provide a shorthand way to perform an operation on a variable and assign the result back to the same variable. Here are the compound assignment operators:

1. Addition and Assignment: +=

x += y; // equivalent to x = x + y;

2. Subtraction and Assignment: -=

x -= y; // equivalent to x = x - y;

3. Multiplication and Assignment: *=

x *= y; // equivalent to x = x * y;

4. Division and Assignment: /=

x /= y; // equivalent to x = x / y;

5. Modulus and Assignment: %=

x %= y; // equivalent to x = x % y;

6. Bitwise AND and Assignment: &=

x &= y; // equivalent to x = x & y;

7. Bitwise OR and Assignment: |=

x |= y; // equivalent to x = x | y;

8. Bitwise XOR and Assignment: ^=

x ^= y; // equivalent to x = x ^ y;

9. Left Shift and Assignment: <<=

x <<= y; // equivalent to x = x << y;

10. Right Shift and Assignment: >>=

x >>= y; // equivalent to x = x >> y;

In summary, compound assignment operators provide a shorthand way to perform an arithmetic or bitwise operation and assign the result back to the same variable. They can help to make code shorter and more readable.