Python match...case Statement

Python3 条件控制Python3 Conditional Control

match...caseIt provides a more powerful pattern matching method.

Pattern matching is a way of processing data structures in programming, making code more concise and readable.

match...caseIt is new syntax introduced in Python 3.10.

match...caseThe syntax structure is as follows:

match expression:
    case pattern1:
        # 处理pattern1的逻辑
    case pattern2 if condition:
        # 处理pattern2并且满足condition的逻辑
    case _:
        # 处理其他情况的逻辑

Parameter description:

  • matchThe statement is followed by an expression, then usecasestatement to define different patterns.
  • caseIt is followed by a pattern, which can be a specific value, variable, wildcard, etc.
  • You can useifkeyword incaseto add conditions.
  • _It is usually used as a wildcard to match any value.

Example

1. Simple Value Matching

Example

def match_example(value):
    match value:
        case 1:
            print("Matched value 1")
        case 2:
            print("Matched value 2")
        case _:
            print("Matched other values")

match_example(1)  # Output: Matched value 1
match_example(2)  # Output: Matched value 2
match_example(3)  # Output: Matched other values

In the above code,matchthe statement is used to matchvaluedifferent cases, eachcasestatement represents a possible matching case,_The wildcard represents other cases.

The output result is:

匹配到值为1
匹配到值为2
匹配到其他值

2. Using Variables

Example

def match_example(item):
    match item:
        case (x, y) if x == y:
            print(f"Matched an equal tuple: {item}")
        case (x, y):
            print(f"Matched a tuple: {item}")
        case _:
            print("Matched other cases")

match_example((1, 1))  #Output:Matched an equal tuple: (1, 1)
match_example((1, 2))  #Output:Matched a tuple: (1, 2)
match_example("other") #Output:Matched other cases

The output result is:

匹配到相等的元组: (1, 1)
匹配到元组: (1, 2)
匹配到其他情况

3. Type Matching

Example

class Circle:
    def __init__(self, radius):
        self.radius = radius

class Rectangle:
    def __init__(self, width, height):
        self.width = width
        self.height = height

def match_shape(shape):
    match shape:
        case Circle(radius=1):
            print("Matched a circle with radius 1")
        case Rectangle(width=1, height=2):
            print("Matched a rectangle with width 1 and height 2")
        case _:
            print("Matched other shapes")

match_shape(Circle(radius=1))          # Output: Matched a circle with radius 1
match_shape(Rectangle(width=1, height=2)) # Output: Matched a rectangle with width 1 and height 2
match_shape("other")                    # Output: Matched other shapes

The output result is:

匹配到半径为1的圆
匹配到宽度为1，高度为2的矩形
匹配到其他形状

Python3 条件控制Python3 Conditional Control

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