"Python Programming Quick Start" Execution of if-elif-else and switch-case in Python

leekom

"Python Programming Quick Start" Execution of if-elif-else and switch-case in Python [Copy link]

In Python, there is no built-in switch-case statement, but you can use dictionary mappings or if-elif-else chains to simulate the behavior of switch-case.

Regarding execution speed, generally speaking, the performance difference between the two is very small and is unlikely to become a bottleneck for program execution. The actual performance difference depends more on the specific usage scenario, the number of conditional branches, and the complexity of the code within each branch.

1. IF-ELSE For simple conditional judgment, the if-elif-else structure is intuitive and easy to understand.

The Python interpreter is optimized for this type of basic structure, so the performance is adequate in most cases.

value = 2

if value == 1:
print("Case 1")
elif value == 2:
print("Case 2")
elif value == 3:
print("Case 3")
else:
print("Default case" )

2. Dictionary mapping (simulating switch-case) Using dictionary mapping can provide a more "Pythonic" way to handle multi-branch selection, which may be more concise in some cases, especially when dealing with a large number of branches.

def case_1():
return "Case 1"

def case_2():
return "Case 2"

def case_3():
return "Case 3"

def default_case():
return "Default case"

switch = {
1: case_1,
2: case_2 ,
3: case_3,
}

value = 2
result = switch.get(value, default_case)()
print(result)

Execution speed comparison In theory, the average time complexity of dictionary lookup (simulating switch-case) is O(1), while the efficiency of the if-elif-else chain decreases slightly as the number of conditions increases, although this difference is often minimal in practical applications and is not enough to be the main factor in deciding which structure to use. In practice, the choice between if-elif-else and dictionary mapping should be based mainly on code readability, maintainability, and specific needs. For simple logic and fewer branches, if-elif-else may be more direct; for complex multi-branch logic, especially when the branch conditions are a fixed set of values, dictionary mapping may provide a clearer and more efficient implementation. In the vast majority of daily development, the performance difference between the two methods is not significant enough to require special consideration.

leekom

lihaodushu01

The author's quick introduction to Python programming is very thorough, and the execution analysis of if-elif-else and switch-case is very thorough. I have to give it a thumbs up.

wangerxian

When pasting Python code, try to use the insert code control, otherwise it will definitely not run if you copy it.

秦天qintian0303

Basically, it is universal and easy to understand. The main difference is the form of expression. Python has very high indentation requirements.