python学习笔记2

就是照着网上的代码敲一敲。

练练手，熟悉一下。

变量类型：

counter = 100 #赋值整型变量
miles = 1000.0 #浮点型
name = "lifei" #字符串

print (counter)
print (miles)
print (name)

print ("3.0这么有意思呢？！~不加括号还不让打印了！！？~")

结果：

SyntaxError: Missing parentheses in call to 'print'. Did you mean print(counter)
?

f:workSpaceForPython>python python变量类型.py
100
1000.0
lifei

f:workSpaceForPython>python python变量类型.py
100
1000.0
lifei
3.0这么有意思呢？！~不加括号还不让打印了！！？~

f:workSpaceForPython>

多个变量赋值

a = b = c = 1
print (a)
print (b)
print (c)

print ("======================")
a , b , c = 1, 2, "john"

print (a)
print (b)
print (c)

结果：

f:workSpaceForPython>python python多个变量赋值.py
1
1
1
======================
1
2
john

 python数字

"""
标准数据类型
python 有五个标准的数据类型：
Numbers (数字)
String （字符串儿）
List    （列表）
Tuple    （元组）
Dictrionary    （字典）
"""

var1 = 1
var2 = 10

print (var1)
print (var2)

del var1,var2

 结果：

f:workSpaceForPython>python pythonnumber.py
1
10

f:workSpaceForPython>python pythonnumber.py
  File "pythonnumber.py", line 17
    del var1[,var2]
             ^
SyntaxError: invalid syntax

f:workSpaceForPython>python pythonnumber.py
1
10

　想说的是：

在这个页面下http://www.runoob.com/python/python-variable-types.html

给出的代码片段是有问题。删除语句并不会写成嵌套那么复杂。。。

就那个 嵌套的语法，有机会的话，可能要深入研究一下。。。

python 字符串

s = 'abcdef'

s = s[1:5]

print (s)

str = "Hello World!"

print (str)
print (str[0])
print (str[2:6])
print (str[2:])
print (str * 2)
print (str+"TEST")

结果：

f:workSpaceForPython>python python字符串.py
bcde
Hello World!
H
llo
llo World!
Hello World!Hello World!
Hello World!TEST

python列表

list = ['lifei',786,2.23,'Letben',70.2]
tinylist = [123,'john']

print (list)    #['lifei',786,2.23,'Letben',70.2]
print (list[0])    #lifei
print (list[1:3])#[786,2.23]
print (list[2:])#[2.23,'Letben',70.2]
print (tinylist * 2)#[123,'john',123,'john']
print (list + tinylist)#['lifei',786,2.23,'Letben',70.2,123,'john']

结果：

f:workSpaceForPython>python python列表.py
['lifei', 786, 2.23, 'Letben', 70.2]
lifei
[786, 2.23]
[2.23, 'Letben', 70.2]
[123, 'john', 123, 'john']
['lifei', 786, 2.23, 'Letben', 70.2, 123, 'john']