python基础

Posted 2023-04-01 以千

1. 序列冒号的使用:-1

a = [0, 1, 2, 3, 4, 5]

print("[0, 1, 2, 3, 4, 5] 测试结果为：")

print("a[-1]-> %s" %a[-1]) ###取最后一个元素

print("a[:-1]-> %s" %a[:-1]) ### 除了最后一个取全部

print("a[::-1]-> %s" %a[::-1]) ### 取从后向前（相反）的元素

print("a[2::-1]-> %s" %a[2::-1]) ### 取从下标为2的元素翻转读取

print("a[3::-1]-> %s" %a[3::-1]) ### 取从下标为3的元素翻转读取

输出结果================================

[0, 1, 2, 3, 4, 5] 测试结果为：

a[-1]-> 5

a[:-1]-> [0, 1, 2, 3, 4]

a[::-1]-> [5, 4, 3, 2, 1, 0]

a[2::-1]-> [2, 1, 0]

a[3::-1]-> [3, 2, 1, 0]

2. 字符串拼接数字输出，占位符号

re = math.floor(32.9)

print("floor(32.9) is ")

print("floor(32.9) is %s" %re)

print("floor(32.9) is %d" %re)

输出结果=====================================

floor(32.9) is

floor(32.9) is 32

floor(32.9) is 32

3. 单双引号及转义字符

print("hello")

print('"hello",he said')

print("\\"Hello, world!\\" she said")

print("hello "+ "world")

#"""这种情况无需转义字符"""

print(""""hello!",he said to her,and 'nice to meet you!',she replyed!""")

#原始字符串,转移字符串在这里面失效

print(r'C:\\Program Files\\python')

输出结果==========================================

hello

"hello",he said

"Hello, world!" she said

hello world

"hello!",he said to her,and 'nice to meet you!',she replyed!

C:\\Program Files\\python

4. 列表 序列

greeting = 'hello'

print("0位置是字母\\"%s\\" -1位置是字母\\"%s\\"" %(greeting[0], greeting[-1]))

#切片----------------------------------------------------------------------------

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

print("#numbers[0:1] is ")

print(numbers[0:1])

print("#numbers[0:2] is ")

print(numbers[0:2])

print("#numbers[-3:-1] is ")

print(numbers[-3:-1])

输出结果=============================================

0位置是字母"h" -1位置是字母"o"

#numbers[0:1] is

[1]

#numbers[0:2] is

[1, 2]

#numbers[-3:-1] is

[8, 9]

#序列相加---------------------------------------------------------------

print("#[1, 2, 3] + [4, 5, 6] is ")

print( [1, 2, 3] + [4, 5, 6])

#in 运算符

permissions = 'we are'

print("""#'w' in permissions""")

print('w' in permissions)

print('we' in permissions)

输出结果======================================

#[1, 2, 3] + [4, 5, 6] is

[1, 2, 3, 4, 5, 6]

#'w' in permissions

True

True

#切片插入----------------------------------------------------------------

numbers = [1,5]

numbers[1:1] = [2,3,4]

print("""#numbers 插入后是""")

print(numbers)

输出结果==============================

#numbers 插入后是

[1, 2, 3, 4, 5]

5. 字符串

#参数--------------------------------------------------------------------------

format = "Hello, %s ,%s end"

values = ("ni",'hao')

print(format % values)

#模板

tmpl= Template("Hello, $chineseyou ,$chinesegood end")

print(tmpl.substitute(chineseyou = "ni",chinesegood = "hao"))

输出结果===========================================

Hello, ni ,hao end

Hello, ni ,hao end

#简单替换方式-----------------------------------------------------------------------

print( "3 0 2 1 3 0".format("be", "not", "or", "to"))

print( "name is approximately value:.2f.".format(value=math.pi, name="π"))

输出结果==============================================

to be or not to be

π is approximately 3.14.

#字段替换顺序和名称 3 2 4 1----------------------------------------------------------

print( "foo 1 bar 0".format(1, 2, bar=4, foo=3))

输出结果===============================================

3 2 4 1

#字符串替换,使用中的fullname----------------------------------------------------------

fullname = ["nash", "sundy"]

print("Mr name[0]".format(name=fullname))

print('One googol is :,'.format(10**100))

print( "Pi is pi:.4f".format(pi=math.pi))

输出结果===================================================

Mr nash

One googol is 10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

Pi is 3.1416

#符号填充-----------------------------------------------------------------------------------------

#所有字符一共12位 000000003.14

print( ':012.2f'.format(math.pi))

#多余空位的对齐方式:左\\居中\\右

print('0:<10.2f\\n0:^10.2f\\n0:>10.2f'.format(math.pi))

输出结果===================================================

000000003.14

3.14

3.14

3.14