一個expression(表達式或運算式)由operators(運算子或運算符)和operands(運算元)所組成。
e.g. 在 $4+5=9$ 這個算式中，用來運算的 $4$ 和 $5$ 稱為operands；而中間的運算符號 $+$ (加號)則稱為operator。
在Python中，有各種不同的operators；operands和運算出的值也可能是各種不同的資料類型。
Python language supports the following types of operators:
| Operator | Name | Example |
|---|---|---|
| + | Addition | a + b |
| - | Subtraction | a - b |
| * | Multiplication | a * b |
| / | Division | a / b |
| % | Modulus (remainder of a / b) | a % b |
| ** | Exponentiation | a ** b |
| // | Floor Division | a // b |
用來比較兩個operand
return a boolean value (True or False)
Suppose a = 10 and b = 20, then:
| Operator | Name | Example |
|---|---|---|
| == | Equal | a == b returns False |
| != | Not Equal | a != b returns True |
| > | Greater Than | a > b returns False |
| < | Less Than | a < b returns False |
| >= | Greater than or Equal to | a >= b returns False |
| <= | Less than or Equal to | a <= b returns False |
<aside>
❗ = is an assignment operator, and == is a comparison operator.
</aside>
除了用來比較數字，也可用於其他資料類型。
# 比較number
a = 10
b = 20
print(a == b) # False
# 比較string
a = "Wilson"
b = "Wilson"
print(a == b) # True
== 來確認所有文字是否皆為小寫。| Operator | Name | Example | Same as |
|---|---|---|---|
| = | Assignment | a = b |
a = b |
| += | Addition Assignment | a += b |
a = a + b |
| -= | Subtraction Assignment | a -= b |
a = a - b |
| *= | Multiplication Assignment | a *= b |
a = a * b |
| /= | Division Assignment | a /= b |
a = a / b |
| %= | Remainder Assignment | a %= b |
a = a % b |
| **= | Exponent Assignment | a **= b |
a = a ** b |
| //= | Floor Division Assignment | a //= b |
a = a // b |
+=, -=, *=, /=, %=, **=, //= 稱為syntax sugar (語法糖：使語法更簡潔或更具可讀性的寫法)。