Python If...Else
Python If…Else (Python If… Else)
Python is an interpreted, high-level, general-purpose programming language that is widely used by programmers worldwide. It is known for its simplicity and readability, making it an excellent choice for beginners and experienced programmers alike. One of the most fundamental aspects of programming in Python is the use of conditions. (Python是一种解释性、高级、通用的编程语言,被世界各地的程序员广泛使用。它以其简单性和可读性而闻名,使其成为初学者和经验丰富的程序员的绝佳选择。Python编程最基本的方面之一是条件的使用。)
Introduction to Python Conditions
Introduction to Python Conditions (Python条件简介)
Conditions in Python are used to make decisions based on whether a particular condition is true or false. The most common type of condition is the “if” statement. This statement evaluates whether a particular expression is true or false and executes a block of code if the expression is true. (Python中的条件用于根据特定条件是TRUE还是FALSE做出决策。最常见的条件类型是“if”语句。此语句评估特定表达式是TRUE还是FALSE ,并在表达式为TRUE时执行代码块。)
The syntax of the “if” statement in Python is as follows:
if expression:
# code to be executed if the expression is true
Let’s look at an example. Suppose we have a variable x that contains the value 5, and we want to check if x is greater than 3. We can use the “if” statement as follows:
x = 5
if x > 3:
print("x is greater than 3")
This code will output “x is greater than 3” because the expression x > 3 is true. (此代码将输出“x大于3” ,因为表达式x > 3为真。)
Python Comparison Operators
Python Comparison Operators (Python比较运算符)
In Python, comparison operators are used to compare two values. The result of the comparison is a boolean value, either True or False. Here are the comparison operators in Python:
greater than (0-大于)
< less than
= greater than or equal to (大於或等於)
<= less than or equal to
== equal to (等于)
!= not equal to (不等于)
We can use these comparison operators in our “if” statements to make decisions based on the values of variables. (我们可以在“if”语句中使用这些比较运算符,根据变量的值做出决策。)
Python Logical Operators
Python Logical Operators (Python逻辑运算符)
Python also has three logical operators: “and”, “or”, and “not”. These operators are used to combine multiple conditions to make more complex decisions.
The “and” operator returns True if both conditions are True, and False otherwise. The “or” operator returns True if either condition is True, and False otherwise. The “not” operator returns the opposite boolean value of the condition. (如果两个条件都为True ,则“and”运算符返回True ,否则返回False。如果条件之一为True ,则“or”运算符返回True ,否则返回False。“not”运算符返回条件的相反布尔值。)
Here’s an example of how to use logical operators in Python:
x = 5
y = 10
if x > 3 and y < 20:
print("Both conditions are true")
This code will output “Both conditions are true” because both conditions in the “if” statement are true. (此代码将输出“两个条件均为真” ,因为“if”语句中的两个条件均为真。)
Python If-Else Statements
Python If-Else Statements (Python If-Else语句)
Sometimes we want to execute a block of code if the condition is true, and a different block of code if the condition is false. We can use the “if-else” statement to accomplish this. (有时,如果条件为true ,我们希望执行一个代码块,如果条件为false ,则执行另一个代码块。我们可以使用“if-else”语句来实现这一点。)
The syntax of the “if-else” statement is as follows:
if expression:
# code to be executed if the expression is true
else:
# code to be executed if the expression is false
Let’s look at an example. Suppose we have a variable x that contains the value 2, and we want to check if x is greater than 3. We can use the “if-else” statement as follows:
x = 2
if x > 3:
print("x is greater than 3")
else:
print("x is less than or equal to 3")
This code will output “x is less than or equal to 3” because the expression x > 3 is false (此代码将输出“x小于或等于3” ,因为表达式x > 3为false)
Python If-Elif-Else Statements
Python If-Elif-Else Statements (Python If-Elif-Else语句)
Sometimes we want to check multiple conditions and execute different blocks of code based on the conditions. We can use the “if-elif-else” statement to accomplish this. (有时,我们希望检查多个条件,并根据条件执行不同的代码块。我们可以使用“if-elif-else”语句来实现这一点。)
The syntax of the “if-elif-else” statement is as follows:
if expression1:
# code to be executed if expression1 is true
elif expression2:
# code to be executed if expression2 is true and expression1 is false
else:
# code to be executed if both expression1 and expression2 are false
Let’s look at an example. Suppose we have a variable x that contains the value 2, and we want to check if x is greater than 3, equal to 3, or less than 3. We can use the “if-elif-else” statement as follows:
x = 2
if x > 3:
print("x is greater than 3")
elif x == 3:
print("x is equal to 3")
else:
print("x is less than 3")
This code will output “x is less than 3” because the expression x > 3 is false and the expression x == 3 is also false. (此代码将输出“x小于3” ,因为表达式x > 3为false ,表达式x = = 3也为false。)
Conclusion
Conclusion (结论)
In conclusion, conditions are an essential aspect of programming in Python. They allow us to make decisions based on the values of variables and execute different blocks of code based on those decisions. By understanding Python conditions, you will be able to write more complex and powerful programs. (总之,条件是Python编程的一个重要方面。它们允许我们根据变量的值做出决策,并根据这些决策执行不同的代码块。通过了解Python条件,您将能够编写更复杂、更强大的程序。)
We hope this article has been helpful in explaining Python conditions. If you have any questions or comments, please feel free to leave them below. (我们希望本文有助于解释Python条件。如果您有任何问题或意见,请在下方留下。)
Thank you for reading, and happy programming! (感谢您的阅读,祝您编程愉快!)