python入门学习(四 Package以及数据类型)
1,Python自带(build-in)package(主要用import导入)和外部(external)package
1.1自带package举例: os包; os.getwd()
2.利用easy_install和pip 来安装扩展文件
2.1 例如 pip install request(s)
3.python 数据类型
3.1 总体上讲: numerics,sequesences,mappings,classes,instances,exceptions.
3.2 Numerics Types: int (包含Boolean),float,complex(复数行)
int:unlimited length;
float 使用C的double实现利用sys.float_info;可以查看
complex: real(实部) imaginary(虚部) 分别用z.real和z.img来区分两部分
具体参见:https://docs.python.org/3/libary/stdtypes.html#numberic-types-int-float-complex
''' Created on 201711 @author: Kevin ''' import sys a = 3 b = 4 c = 5.5 d = 6.5 e = complex(c,d) f = complex(float(a),float(b)) print("a is type: ",type(a)) #type 是查看数据类型 print("a is type: ",type(c)) #type 是查看数据类型 print("a is type: ",type(e)) #type 是查看数据类型 print(a+b) #加 print(d/c) #除 print(b/a) #除 print(b//a) #两个除号四舍五入取整 print(e) print(e+f) print(sys.float_info)#float的具体信息
a is type: <class 'int'> a is type: <class 'float'> a is type: <class 'complex'> 7 1.1818181818181819 1.3333333333333333 1 (5.5+6.5j) (8.5+10.5j) sys.float_info(max=1.7976931348623157e+308, max_exp=1024, max_10_exp=308, min=2.2250738585072014e-308, min_exp=-1021, min_10_exp=-307, dig=15, mant_dig=53, epsilon=2.220446049250313e-16, radix=2, rounds=1)