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python的變量和簡單數(shù)字類型詳解

更新時間：2021年09月14日 14:42:57 作者：CV_Begineer

這篇文章給大家詳細(xì)介紹了python的變量和簡單數(shù)字類型，文中介紹的很詳細(xì)，相信對大家的理解和學(xué)習(xí)很有幫助，有需要的朋友們可以參考借鑒

1. 變量

每個變量都存儲了一個值
在程序中可以隨時修改變量，但Python將始終記錄變量的最新值

message = "Hello Huang ZB!"
print(message)
message = "Goodbye Huang ZB!"
print(message)

1.1 使用變量名時避免命名錯誤

查看Traceback明白錯誤

message = "Hello Huang ZB!"
print(mesage)

2.字符串

Def：字符串就是一串字符。雙引號、單引號都可表示

2.1 修改字符串大小寫的方法

name = "huang zhibin"
print(name.title())            #title()函數(shù)作用：將每個單詞首字母改為大寫

Huang Zhibin

其他方法：

name = "huang zhibin"
print(name.title())   #title()函數(shù)作用：將每個單詞首字母改為大寫
print(name.upper())   #upper()函數(shù)作用：將字符串內(nèi)容全部轉(zhuǎn)換為大寫
print(name.lower())   #lower()函數(shù)作用：將字符串內(nèi)容全部轉(zhuǎn)換為小寫

Huang Zhibin
HUANG ZHIBIN
huang zhibin

2.2 合并字符串

方法：拼接

first_name = 'huang'
last_name = 'zhibin'
full_name = first_name + ' ' + last_name
print('Hello, ' + full_name.title() + '!')    #這個 + 不可或缺

Hello, Huang Zhibin!

2.3 使用制表符或換行符來添加空白

在字符串中添加制表符，使用 \t (也可以理解為進(jìn)位符)

print("python")
print("\tpython")             # \t 表示制表符

python
python

在字符串中添加換行符，使用 \n

print("Languages:\nPython\nC\nJavaScript")       # \n 表示換行符

Languages:
Python
C
JavaScript

同一字符串中可以同時包含制表符和換行符字符串" \n\t ": 讓python換到下一行

print("Languages:\n\tPython\n\tC\n\tJavaScript")

Languages:
Python
C
JavaScript

2.4 刪除空白

python能夠找出字符串開頭和末尾多余的空白，為確保開末尾無空白，使用方法 rstrip()
為確保開開頭無空白，使用方法 lstrip()
同時剔除字符串兩端的空白，使用方法 strip()

information = '    人生苦短，我學(xué)python    '
print(information.rstrip())
print(information.lstrip())
print(information.strip())

人生苦短，我學(xué)python

人生苦短，我學(xué)python #右邊空格依然存在！

人生苦短，我學(xué)python

2.5 使用字符串時需要避免語法錯誤

再修改程序時語法錯誤也是一個重要的檢查指標(biāo)

3. 數(shù)字類型

3.1 整數(shù)

>>> 2+3
5
>>> 5-6
-1
>>> 4*5
20
>>> 36/6
6.0
>>> 3**2
9
>>> 2+2**2
6
>>> (2+2)*2
8

3.2 浮點(diǎn)數(shù)

>>> 0.2+0.3
0.5
>>> 0.2-0.3
-0.09999999999999998

保留兩位小數(shù)

print ('{:.2}'.format(變量))

3.3 復(fù)數(shù)

>>> 2+6j
(2+6j)
>>> (2+6j).real
2.0
>>> (2+6j).imag
6.0

3.4 使用函數(shù)str()避免類型錯誤

age = 21
message = "Happy " + str(age) + "rd Birthday!"     #將非字符串值轉(zhuǎn)化為字符串
print(message)

Happy 21rd Birthday!

4 .注釋

單行注釋

#

多行注釋

‘''

注釋不能嵌套?。。。?！

5 .python之禪

>>> import this
The Zen of Python, by Tim Peters
Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!