In C++, **operator precedence** determines the * order in which operators are evaluated* in a complex expression. Understanding this is important for writing

*(and interpreting)*expressions correctly and avoiding unexpected errors in your programs.

Operators with higher precedence are evaluated before operators with lower precedence. If two operators have the same precedence, their evaluation is determined by the operator’s associativity *(left to right or right to left).

If you want to learn more about Operator Precedence

check out the **Introduction to Programming Course** read more

### Operator Precedence Table

Here is a table with the precedence of operators in C++, from highest to lowest. The highest precedence is evaluated first:

Priority | Operator | Description | Associativity |
---|---|---|---|

1 | `()` | Parentheses | N/A |

2 | `++` , `--` | Increment and decrement (postfix) | Right to left |

3 | `+` , `-` | Unary plus and minus | Right to left |

4 | `*` , `/` , `%` | Multiplication, division, modulus | Left to right |

5 | `+` , `-` | Addition, subtraction | Left to right |

6 | `<<` , `>>` | Bitwise shift | Left to right |

7 | `<` , `>` , `<=` , `>=` | Comparison | Left to right |

8 | `==` , `!=` | Equality, inequality | Left to right |

9 | `&` | Bitwise AND | Left to right |

10 | `^` | Bitwise XOR | Left to right |

11 | ` | ` | Bitwise OR |

12 | `&&` | Logical AND | Left to right |

13 | ` | ` | |

14 | `?:` | Conditional operator (ternary) | Right to left |

15 | `=` , `+=` , `-=` | Assignment and compound operators | Right to left |

## How Operator Precedence Works

### Expression Evaluation

Operator precedence determines the order in which operators are evaluated in an expression. For example, consider the following expression:

`int result = 3 + 4 * 2; // equivalent to 3 + (4 * 2) = 11`

Here, the multiplication operator (`*`

) has a higher precedence than the addition operator (`+`

). Therefore, `4 * 2`

is evaluated first, resulting in `8`

, and then `3`

is added, resulting in `11`

.

### Using Parentheses

To change the order of evaluation, you can use parentheses. Parentheses have the highest precedence and force the evaluation of the expression they contain first:

`int result = (3 + 4) * 2;`

In this case, `3 + 4`

is evaluated first due to the parentheses, resulting in `7`

, and then multiplied by `2`

, resulting in `14`

.

### Associativity

When operators have the same precedence, associativity is applied to determine the order of evaluation. Most operators in C++ have left-to-right associativity.

```
int a = 1;
int b = 2;
int c = 3;
int result = a + b - c; // Evaluated as ((a + b) - c)
```

Here, both `+`

and `-`

have the same precedence and left-to-right associativity, so `a + b`

is evaluated first and then `c`

is subtracted.

However, some operators, such as assignment operators and the conditional ternary operator, have right-to-left associativity.

## Complex Example

Let’s consider the following expression:

`int result = 5 + 2 * 3 - 4 / 2 + (1 + 3);`

We will evaluate it step by step according to precedence and associativity:

- Evaluate the expression in parentheses:
`(1 + 3)`

, which results in`4`

. - Evaluate the multiplication:
`2 * 3`

, which results in`6`

. - Evaluate the division:
`4 / 2`

, which results in`2`

. - Evaluate the remaining operations from left to right:
`5 + 6`

results in`11`

.`11 - 2`

results in`9`

.`9 + 4`

results in`13`

.

Thus, the final result of the expression is `13`

.

## Best Practices Advice

Although operator precedence allows for omitting parentheses in many situations, it is good practice to use parentheses to improve code clarity. This not only makes the code easier to understand but also reduces the likelihood of errors.

`int result = (5 + 2) * (3 - 1);`