数据类型相关函数
type() 查看数据类型
#!/usr/bin/env python
# -*- coding:utf-8 -*-
# @Time : 2017/10/17 21:46
# @Author : lijunjiang
# @File : test.py
# type() 查看数据类型
name = raw_input("Please input your name: ")
print(name)
print(type(name))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
Please input your name: lijunjiang
lijunjiang
<type 'str'>
Process finished with exit code 0
raw_input() 接收字符串和非字符串输入，类型均为字符串
name = raw_input("Please input your name: ")
print(name)
print(type(name))
age = raw_input("Please input your age: ")
print(age)
print(type(age))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
Please input your name: lijunjiang
lijunjiang
<type 'str'>
Please input your age: 18
18
<type 'str'>
Process finished with exit code 0
input () 只接收整型
age = input("Please input your age: ")
print(age)
print(type(age))
name = input("Please input your name: ")
print(name)
print(type(name))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
Please input your age: 18
18
<type 'int'>
Please input your name: lijunjiang
Traceback (most recent call last):
File "D:/Python/type_of-data.py", line 26, in <module>
name = input("Please input your name: ")
File "<string>", line 1, in <module>
NameError: name 'lijunjiang' is not defined
Process finished with exit code 1
abs() 或 __abs__ 取绝对值
a = 100
b = -30
print(a)
print(b)
print(a - b)
print(a.__abs__() + b.__abs__())
print(abs(a) + abs(b))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
100
-30
130
130
130
Process finished with exit code 0
dir() 列出一个定义对象的标识符
当你给dir()提供一个模块名字时，它返回在那个模块中定义的名字的列表。当没有为其提供参数时, 它返回当前模块中定义的名字的列表。
a = 18
b = "lijunjiang"
print(dir())
print(dir(a))
print(dir(b))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
#当前模块定义的名子和列表
['__builtins__', '__doc__', '__file__', '__name__', '__package__', 'a', 'b']
#整型 方法
['__abs__', '__add__', '__and__', '__class__', '__cmp__', '__coerce__', '__delattr__', '__div__', '__divmod__', '__doc__', '__float__', '__floordiv__', '__format__', '__getattribute__', '__getnewargs__', '__hash__', '__hex__', '__index__', '__init__', '__int__', '__invert__', '__long__', '__lshift__', '__mod__', '__mul__', '__neg__', '__new__', '__nonzero__', '__oct__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', '__rdiv__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', '__rxor__', '__setattr__', '__sizeof__', '__str__', '__sub__', '__subclasshook__', '__truediv__', '__trunc__', '__xor__', 'bit_length', 'conjugate', 'denominator', 'imag', 'numerator', 'real']
#字符串 方法
['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']
Process finished with exit code 0
整型(int)
即整数
a = 100
b = 20
print(type(a))
print(type(b))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
<type 'int'>
<type 'int'>
Process finished with exit code 0
浮点型(float)
即小数 在python中整型后加小数点可定义浮点型数据
a = 10
b = 10.0
print(type(a))
print(type(b))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
<type 'int'>
<type 'float'>
Process finished with exit code 0
round(n[, x]) 返回浮点数n四舍五入值，x保留位数，默认为0 ，大于0对小数部分四舍五入，小于0对整数部分四舍五入，返回结果为浮点数
a = 10
b = 11.455
c = 15.345
print(round(a))
print(round(a, 1))
print(round(a, 2))
print(round(b))
print(round(b, 1))
print(round(b, 2))
print(round(c))
print(round(c, 1))
print(round(c, 2))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
10.0
10.0
10.0
11.0
11.5
11.46
15.0
15.3
15.35
Process finished with exit code 0
round 负数( 四舍五入是围绕着0来计算的)
print(round(0.4))
print(round(-0.4))
print(round(0.5))
print(round(-0.5))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
0.0
-0.0
1.0
-1.0
Process finished with exit code 0
round 的陷阱
print(round(1.675, 2))
print(round(2.675, 2))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
1.68
2.67
Process finished with exit code 0
布尔型（）
就两值 真（True）或假（False）
一般用作一个判断的返回值
print(not True)
print(not False)
a = 10
b = 20
c = 50
print(a > b and c > a)
print(not(a > b and c > a))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
False
True
False
True
Process finished with exit code 0
字符串（str）
定义：使用 ''、 ""、""""""、声明一个字符串，phthon默认使用单引号
a = 'aaaaa'
b = "bbbbb"
c = """ccccc"""
print(a)
print('a %s' % type(a))
print(b)
print('b %s' % type(b))
print(c)
print('c %s' % type(c))
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
aaaaa
a <type 'str'>
bbbbb
b <type 'str'>
ccccc
c <type 'str'>
Process finished with exit code 0
字符串常用方法
0、''''''
常用于多行注释，起解释作用
1、下标
a = 'abcde'
print(a[0], a[1], a[2], a[3], a[4])
执行结果：
C:Python27python.exe D:/Python/type_of-data.py
('a', 'b', 'c', 'd', 'e')
Process finished with exit code 0
2、find() 在字符串中查找字符串，返回查找字符串中第一个字符的下标，未找到返回-1
a = 'aabbcc'
print(a.find('b'))
print(a.find('e'))
执行：
C:Python27python.exe D:/Python/type_of-data.py
2
-1
Process finished with exit code 0
3、replace(str1,str2) 替换 将str1替换为str2
a = 'aabbcbccc'
print(a.replace('bb', 'ff'))
print(a.replace('bc','qq'))
print(a.replace('c', 'RR'))
执行：
C:Python27python.exe D:/Python/type_of-data.py
aaffcbccc
aabqqqqcc
aabbRRbRRRRRR
Process finished with exit code 0
4、split(srt) 分割 以str 为分割符，返回一个列表 类似shell中awk -F
a = 'aaTbbTccTbb'
print(a.split('T'))
执行：
C:Python27python.exe D:/Python/type_of-data.py
['aa', 'bb', 'cc', 'bb']
Process finished with exit code 0
5、join(str) 以str连接字符串
a = 'aaTbbTccTbb'
print('||'.join(a.split('T')))
print(' '.join(a.split('T')))
执行：
C:Python27python.exe D:/Python/type_of-data.py
aa||bb||cc||bb
aa bb cc bb
Process finished with exit code 0
等价于：
a = 'aaTbbTccTbb'
a = a.split('T')
print(a)
print("||".join(a))
print(' '.join(a))
执行：
C:Python27python.exe D:/Python/type_of-data.py
['aa', 'bb', 'cc', 'bb']
aa||bb||cc||bb
aa bb cc bb
Process finished with exit code 0
5、strip() 去除字符串两边的空格
lstrip() 只去除左边空格 rstrip() 只去除右边空格
a = ' aa bb cc '
print(a)
print(a.strip())
print(a.lstrip())
print(a.rstrip())
b = ' aa bb cc '
print(b)
print(b.strip())
print(b.lstrip())
print(b.rstrip())
执行：
C:Python27python.exe D:/Python/type_of-data.py
aa bb cc
aa bb cc
aa bb cc
aa bb cc
aa bb cc
aa bb cc
aa bb cc
aa bb cc
Process finished with exit code 0
6、format
print('str0 {0} str1{1}'.format(str0, str1)) 执行效率最高
a = 'python'
b = 'Hi, '
print('hello' + a)
print('hello %s') % a
print('hello %{0}'.format(a))
print('hello {0}'.format(a))
print('hello {}'.format(a))
print('hello {a}'.format(a='python'))
print('###########' * 20)
print(b + 'hello ' + a)
print('%s hello %s') % (b, a)
print('%{0} hello %{1}'.format(b, a))
print('{0} hello {1}'.format(b, a))
print('{} hello {}'.format(b, a))
print('{a} hello {b}'.format(a='Hi,', b='python'))
执行：
C:Python27python.exe D:/Python/type_of-data.py
hellopython
hello python
hello %python
hello python
hello python
hello python
############################################################################################################################################################################################################################
Hi, hello python
Hi, hello python
%Hi, hello %python
Hi, hello python
Hi, hello python
Hi, hello python
Process finished with exit code 0