Python 代码片段 |文档

王林

发布时间：2024-08-31 12:33:03

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python 代码片段 |文档

python 课程代码示例

这是我使用和创建的 python 代码的文档，用于学习 python。
它易于理解和学习。欢迎从这里学习。
我很快就会用更多高级主题更新博客。

第一个节目

此程序用于展示 print() 命令如何工作。

# this is a simple "hello world" program that demonstrates basic print statements

# print the string "hello world" to the console
print("hello world")

# print the integer 1 to the console
print(1)

# print the integer 20 to the console
print(20)

变量和数据类型

python 中的变量是用于存储值的保留内存位置。
数据类型定义变量可以保存的数据类型，即整数、浮点、字符串等

# this program demonstrates the use of variables and string concatenation

# assign the string "dipsan" to the variable _name
_name = "dipsan"

# assign the integer 20 to the variable _age
_age = 20

# assign the string "piano" to the variable _instrument
_instrument = "piano"

# print a sentence using string concatenation with the _name variable
print("my name is" + _name + ".")

# print a sentence using string concatenation, converting _age to a string
print("i'm" + str(_age) + "years old")  # converting int to string for concatenation

# print a simple string
print("i dont like hanging out")

# print a sentence using string concatenation with the _instrument variable
print("i love " + _instrument + ".")

弦乐

用于存储和操作文本的字符序列。它们是通过将文本括在单引号 ('hello')、双引号 ("hello") 或多行字符串的三引号 ('''hello''') 中来创建的。示例：“你好，世界！”。

# this script demonstrates various string operations

# assign a string to the variable 'phrase'
phrase = "dipsansacademy"

# print a simple string
print("this is a string")

# concatenate strings and print the result
print('this' + phrase + "")

# convert the phrase to uppercase and print
print(phrase.upper())

# convert the phrase to lowercase and print
print(phrase.lower())

# check if the uppercase version of phrase is all uppercase and print the result
print(phrase.upper().isupper())

# print the length of the phrase
print(len(phrase))

# print the first character of the phrase (index 0)
print(phrase[0])

# print the second character of the phrase (index 1)
print(phrase[1])

# print the fifth character of the phrase (index 4)
print(phrase[4])

# find and print the index of 'a' in the phrase
print(phrase.index("a"))

# replace "dipsans" with "kadariya" in the phrase and print the result
print(phrase.replace("dipsans", "kadariya"))

数字

数字用于各种数字运算和数学函数：

# import all functions from the math module
from math import *  # importing math module for additional math functions

# this script demonstrates various numeric operations and math functions

# print the integer 20
print(20)

# multiply 20 by 4 and print the result
print(20 * 4)

# add 20 and 4 and print the result
print(20 + 4)

# subtract 4 from 20 and print the result
print(20 - 4)

# perform a more complex calculation and print the result
print(3 + (4 - 5))

# calculate the remainder of 10 divided by 3 and print the result
print(10 % 3)

# assign the value 100 to the variable _num
_num = 100

# print the value of _num
print(_num)

# convert _num to a string, concatenate with other strings, and print
print(str(_num) + " is my fav number")  # converting int to string for concatenation

# assign -10 to the variable new_num
new_num = -10

# print the absolute value of new_num
print(abs(new_num))  # absolute value

# calculate 3 to the power of 2 and print the result
print(pow(3, 2))     # power function

# find the maximum of 2 and 3 and print the result
print(max(2, 3))     # maximum

# find the minimum of 2 and 3 and print the result
print(min(2, 3))     # minimum

# round 3.2 to the nearest integer and print the result
print(round(3.2))    # rounding

# round 3.7 to the nearest integer and print the result
print(round(3.7))

# calculate the floor of 3.7 and print the result
print(floor(3.7))    # floor function

# calculate the ceiling of 3.7 and print the result
print(ceil(3.7))     # ceiling function

# calculate the square root of 36 and print the result
print(sqrt(36))      # square root

获取用户的输入

此程序用于演示如何使用 input() 函数获取用户输入：

# this script demonstrates how to get user input and use it in string concatenation

# prompt the user to enter their name and store it in the 'name' variable
name = input("enter your name : ")

# prompt the user to enter their age and store it in the 'age' variable
age = input("enter your age. : ")

# print a greeting using the user's input, concatenating strings
print("hello " + name + " youre age is " + age + " .")

构建一个基本计算器

该程序创建一个简单的计算器，将两个数字相加：

# this script creates a basic calculator that adds two numbers

# prompt the user to enter the first number and store it in 'num1'
num1 = input("enter first number : ")

# prompt the user to enter the second number and store it in 'num2'
num2 = input("enter second number: ")

# convert the input strings to integers and add them, storing the result
result = int(num1) + int(num2)

# print the result of the addition
print(result)

第一疯狂

这个程序创建了一个简单的 mad libs 游戏：

# this program is used to create a simple mad libs game.

# prompt the user to enter an adjective and store it in 'adjective1'
adjective1 = input("enter an adjective: ")

# prompt the user to enter an animal and store it in 'animal'
animal = input("enter an animal: ")

# prompt the user to enter a verb and store it in 'verb'
verb = input("enter a verb: ")

# prompt the user to enter another adjective and store it in 'adjective2'
adjective2 = input("enter another adjective: ")

# print the first sentence of the mad libs story using string concatenation
print("i have a " + adjective1 + " " + animal + ".")

# print the second sentence of the mad libs story
print("it likes to " + verb + " all day.")

# print the third sentence of the mad libs story
print("my " + animal + " is so " + adjective2 + ".")

列表

列表是python中有序且可更改的项目的集合。列表中的每个项目（或元素）都有一个索引，从 0 开始。列表可以包含不同数据类型的项目（如整数、字符串，甚至其他列表）。
列表使用方括号 [] 定义，每个项目用逗号分隔。

# this script demonstrates basic list operations

# create a list of friends' names
friends = ["roi", "alex", "jimmy", "joseph"]

# print the entire list
print(friends)

# print the first element of the list (index 0)
print(friends[0])

# print the second element of the list (index 1)
print(friends[1])

# print the third element of the list (index 2)
print(friends[2])

# print the fourth element of the list (index 3)
print(friends[3])

# print the last element of the list using negative indexing
print(friends[-1])

# print a slice of the list from the second element to the end
print(friends[1:])

# print a slice of the list from the second element to the third (exclusive)
print(friends[1:3])

# change the second element of the list to "kim"
friends[1] = "kim"

# print the modified list
print(friends)

列表功能

此脚本展示了各种列表方法：

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# this script demonstrates various list functions and methods

# create a list of numbers
numbers = [4, 6, 88, 3, 0, 34]

# create a list of friends' names
friends = ["roi", "alex", "jimmy", "joseph", "kevin", "tony", "jimmy"]

# print both lists
print(numbers)
print(friends)

# add all elements from 'numbers' to the end of 'friends'
friends.extend(numbers)

# add "hulk" to the end of the 'friends' list
friends.append("hulk")

# insert "mikey" at index 1 in the 'friends' list
friends.insert(1, "mikey")

# remove the first occurrence of "roi" from the 'friends' list
friends.remove("roi")

# print the index of "mikey" in the 'friends' list
print(friends.index("mikey"))

# remove and print the last item in the 'friends' list
print(friends.pop())

# print the current state of the 'friends' list
print(friends)

# remove all elements from the 'friends' list
friends.clear()

# print the empty 'friends' list
print(friends)

# sort the 'numbers' list in ascending order
numbers.sort()

# print the sorted 'numbers' list
print(numbers)

元组

元组是python中有序但不可更改（不可变）的项目的集合。一旦创建了元组，就无法添加、删除或更改其元素。与列表一样，元组可以包含不同数据类型的项目。
元组使用括号 () 定义，每个项目用逗号分隔。

# this script introduces tuples and their immutability

# create a tuple with two elements
values = (3, 4)

# print the entire tuple
print(values)

# print the second element of the tuple (index 1)
print(values[1])

# the following line would cause an indexerror if uncommented:
# print(values[2])  # this would cause an indexerror

# the following line would cause a typeerror if uncommented:
# values[1] = 30    # this would cause a typeerror as tuples are immutable

# the following line would print the modified tuple if the previous line worked:
# print(values)

功能

函数是执行特定任务的可重用代码块。函数可以接受输入（称为参数）、处理它们并返回输出。函数有助于组织代码，使其更加模块化，并避免重复。
在 python 中，函数是使用 def 关键字定义的，后跟函数名、括号 () 和冒号 :。函数内的代码是缩进的。
此代码演示了如何定义和调用函数：

# this script demonstrates how to define and call functions

# define a function called 'greetings' that prints two lines
def greetings():
    print("hi, welcome to programming world of python")
    print("keep learning")

# print a statement before calling the function
print("this is first statement")

# call the 'greetings' function
greetings()

# print a statement after calling the function
print("this is last statement")

# define a function 'add' that takes two parameters and prints their sum
def add(num1, num2):
    print(int(num1) + int(num2))

# call the 'add' function with arguments 3 and 4
add(3, 4)

退货声明

return 语句在函数中用于向调用者发送回（或“返回”）一个值。当执行return时，函数结束，return后指定的值被发送回函数调用的地方。

此程序展示了如何在函数中使用 return 语句：

# this script demonstrates the use of return statements in functions

# define a function 'square' that returns the square of a number
def square(num):
    return num * num
    # any code after the return statement won't execute

# call the 'square' function with argument 2 and print the result
print(square(2))

# call the 'square' function with argument 4 and print the result
print(square(4))

# call the 'square' function with argument 3, store the result, then print it
result = square(3)
print(result)

如果语句

if 语句计算一个条件（返回 true 或 false 的表达式）。
如果条件为 true，则执行 if 语句下的代码块。
elif ：“else if”的缩写，它允许您检查多个条件。
当您有多个条件需要评估，并且您想要执行第一个 true 条件的代码块时，可以使用它。
else：如果前面的 if 或 elif 条件都不为 true，则 else 语句将运行一段代码。

# this script demonstrates the use of if-elif-else statements

# set boolean variables for conditions
is_boy = true
is_handsome = false

# check conditions using if-elif-else statements
if is_boy and is_handsome:
    print("you are a boy & youre handsome")
    print("hehe")
elif is_boy and not (is_handsome):
    print("youre a boy but sorry not handsome")
else:
    print("youre not a boy")

如果比较

此代码演示了 if 语句中的比较操作：

# this script demonstrates comparison operations in if statements

# define a function to find the maximum of three numbers
def max_numbers(num1, num2, num3):
    if num1 >= num2 and num1 >= num3:
        return num1
    elif num2 >= num1 and num2 >= num3:
        return num2
    else:
        return num3

# test the max_numbers function with different inputs
print(max_numbers(20, 40, 60))
print(max_numbers(30, 14, 20))
print(max_numbers(3, 90, 10))

print("for min_number")

# define a function to find the minimum of three numbers
def min_numbers(num1, num2, num3):
    if num1 <= num2 and num1 <= num3:
        return num1
    elif num2 <= num1 and num2 <= num3:
        return num2
    else:
        return num3

# test the min_numbers function with different inputs
print(min_numbers(20, 40, 60))
print(min_numbers(30, 14, 20))
print(min_numbers(3, 90, 10))

猜谜游戏2

此脚本通过更多功能改进了猜谜游戏：

# this script improves the guessing game with more features

import random

# generate a random number between 1 and 20
secret_number = random.randint(1, 20)

# initialize the number of attempts and set a limit
attempts = 0
attempt_limit = 5

# loop to allow the user to guess the number
while attempts < attempt_limit:
    guess = int(input(f"guess the number (between 1 and 20). you have {attempt_limit - attempts} attempts left: "))
    if guess == secret_number:
        print("congratulations! you guessed the number!")
        break
    elif guess < secret_number:
        print("too low!")
    else:
        print("too high!")
    attempts += 1

# if the user does not guess correctly within the attempt limit, reveal the number
if guess != secret_number:
    print(f"sorry, the correct number was {secret_number}.")

for循环

for 循环用于迭代元素序列，例如列表、元组、字符串或范围。
这段代码引入了for循环：

# list of numbers
numbers = [1, 2, 3, 4, 5]

# iterate over each number in the list
for number in numbers:
    # print the current number
    print(number)

# output:
# 1
# 2



# 3
# 4
# 5

# list of friends
friends = ["roi", "alex", "jimmy", "joseph", "kevin", "tony", "jimmy"]

# iterate over each friend in the list
for friend in friends:
    # print the name of the current friend
    print(friend)

# output:
# roi
# alex
# jimmy
# joseph
# kevin
# tony
# jimmy

# use range to generate numbers from 0 to 4
for num in range(5):
    print(num)

# output:
# 0
# 1
# 2
# 3
# 4

指数函数

指数函数是一种数学函数，其中恒定基数被提升为可变指数。
此脚本展示了如何使用 math.pow 函数：

# this script demonstrates the use of the exponential function
def exponentialfunction(base,power):
    result = 1
    for index in range(power):
        result = result * base
    return result

print(exponentialfunction(3,2))
print(exponentialfunction(4,2))
print(exponentialfunction(5,2))

#or you can power just by
print(2**3) #number *** power

2d 列表和 for 循环

python 中的 2d 列表（或 2d 数组）本质上是列表的列表，其中每个子列表代表矩阵的一行。您可以使用嵌套的 for 循环来迭代 2d 列表中的元素。以下是使用 2d 列表和 for 循环的方法：

# This script demonstrates the use of 2D List and For Loops
# Define a 2D list (list of lists)
num_grid = [
    [1, 2, 3],  # Row 0: contains 1, 2, 3
    [4, 5, 6],  # Row 1: contains 4, 5, 6
    [7, 8, 9],  # Row 2: contains 7, 8, 9
    [0]         # Row 3: contains a single value 0
]

# Print specific elements in num_grid
print(num_grid[0][0])   # Print value in the zeroth row, zeroth column (value: 1)
print(num_grid[1][0])   # Print value in the first row, zeroth column (value: 4)
print(num_grid[2][2])   # Print value in the second row, second column (value: 9)


print("using nested for loops")
for row in num_grid :
   for col in row:
    print(col)

这就是我们如何使用 2d 列表和 for 循环。

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