控制流是编程语言中用来控制程序执行顺序的机制。在 Python 中，有几种主要的控制流结构，包括条件语句、循环语句等。

条件语句

在 Python 中，使用 if 语句来实现条件判断。

if condition:
    # 条件为真时执行的代码

例如，我们可以使用 if 语句来判断一个数字是否为偶数：

num = 10
if num % 2 == 0:
    print("这是一个偶数")

循环语句

Python 中有几种循环语句，包括 for 和 while。

For 循环

for 循环用于遍历序列（如列表、元组、字符串）中的每个元素。

for element in sequence:
    # 循环体

例如，我们可以使用 for 循环遍历一个列表并打印每个元素：

numbers = [1, 2, 3, 4, 5]
for number in numbers:
    print(number)

While 循环

while 循环用于在满足特定条件时重复执行代码块。

while condition:
    # 循环体

例如，我们可以使用 while 循环来计算一个数的阶乘：

num = 5
result = 1
while num > 1:
    result *= num
    num -= 1
print(result)

图片示例

这里是一个关于 Python 控制流的图片示例：

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# Python 控制流教程

# 控制流是编程语言中用来控制程序执行顺序的 mechanism。In Python, there are several main control flow structures, including conditional statements, loop statements, etc.

# Conditional Statements

In Python, `if` statements are used for conditional judgments.

```python
if condition:
    # Code to execute when the condition is true

For example, we can use the if statement to determine if a number is even:

num = 10
if num % 2 == 0:
    print("This is an even number")

Loop Statements

Python has several loop statements, including for and while.

For Loop

The for loop is used to iterate over each element in a sequence (such as a list, tuple, or string).

for element in sequence:
    # Loop body

For example, we can use the for loop to traverse a list and print each element:

numbers = [1, 2, 3, 4, 5]
for number in numbers:
    print(number)

While Loop

The while loop is used to repeatedly execute a code block when a specific condition is met.

while condition:
    # Loop body

For example, we can use the while loop to calculate the factorial of a number:

num = 5
result = 1
while num > 1:
    result *= num
    num -= 1
print(result)

Image Example

Here is an example image about Python control flow:

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