Deeply master the flow control statements and logical operations in Python

In-depth understanding of flow control statements and logical operators in Python

In the Python programming language, flow control statements and logical operators implement conditional judgments and loops Important section. Through the flexible use of flow control statements and logical operators, we can execute different code blocks based on different conditions and repeatedly execute specific code blocks. In this article, we will provide an in-depth understanding of flow control statements and logical operators in Python and provide specific code examples.

1. Process control statement

1. If statement:

The If statement is the most basic conditional judgment statement in Python, used to determine based on different conditions Execute different blocks of code. Its basic syntax is as follows:

if condition:
    block of code

Among them, condition is a Boolean expression. If the condition is true, the code in the block of code will be executed; if the condition is false, the code block will be skipped.

The following is a specific example:

x = 5
if x > 0:
    print("x是正数")

In this example, if the value of variable x is greater than 0, "x is a positive number" will be printed.

2. If-else statement:

The If-else statement is a flow control statement that executes another piece of code when the If condition is false. The basic syntax is as follows:

if condition:
    block of code
else:
    block of code

If condition is true, the first code block is executed; if condition is false, the code block after else is executed.

The following is a specific example:

x = -5
if x > 0:
    print("x是正数")
else:
    print("x是负数")

In this example, if the value of variable x is greater than 0, "x is a positive number" will be printed; otherwise, "x" will be printed is a negative number".

3. If-elif-else statement:

The If-elif-else statement can execute different code blocks based on multiple conditional judgments. The basic syntax is as follows:

if condition1:
    block of code
elif condition2:
    block of code
else:
    block of code

If condition1 is true, execute the first code block; if condition1 is false and condition2 is true, execute the second code block; otherwise, execute the code block after else .

The following is a specific example:

x = 0
if x > 0:
    print("x是正数")
elif x < 0:
    print("x是负数")
else:
    print("x是零")

In this example, if the value of variable x is greater than 0, "x is a positive number" will be printed; if the value of x is less than 0, will print out "x is a negative number"; otherwise, it will print out "x is zero".

2. Logical operators

In Python, logical operators are used to combine multiple expressions into a more complex expression for conditional judgment and looping. Commonly used logical operators include the following:

1. And operator (and):

The AND operator is used to determine whether two conditions are true at the same time, that is, only The entire expression is true when both conditions are true.

The following is a specific example:

x = 5
if x > 0 and x < 10:
    print("x是一个介于0和10之间的数")

In this example, when the value of variable x is greater than 0 and less than 10, it will print out "x is a value between 0 and 10 number between".

2. Or operator (or):

The or operator is used to determine whether one of two conditions is true, that is, as long as one condition is true, the entire expression Just be true.

The following is a specific example:

x = 5
if x < 0 or x > 10:
    print("x是一个负数或大于10的数")

In this example, as long as the value of variable x is less than 0 or greater than 10, it will print out "x is a negative number or a number greater than 10 ".

3. Non-operator (not):

The non-operator is used to negate the condition, that is, if the condition is true, the entire expression is false; If the condition is false, the entire expression is true.

The following is a specific example:

x = 5
if not x > 10:
    print("x不是一个大于10的数")

In this example, when the value of variable x is not greater than 10, "x is not a number greater than 10" will be printed.

By flexibly using flow control statements and logical operators, we can execute different code blocks according to different conditions and repeatedly execute specific code blocks. I hope this article can help you have a deeper understanding of flow control statements and logical operators in Python, and be able to use them skillfully in actual programming.

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