第六章：条件、循环

第1讲：基础技能的补充

 

　　1.print函数的总结

print("hello world!")
print("hello "+"world!")
name = "Bela"
print(name)
print("your name is:",name)
print(1,2,3)
print((1,2,3))
print("==========")
age = 19
# Bela age is 19
print(name,"age is",age)

结果：

hello world!
hello world!
Bela
your name is: Bela
1 2 3
(1, 2, 3)
==========
Bela age is 19

# 变量不允许+连接，会出错
print(name+"age is"+age)

结果：
Traceback (most recent call last):
  File "C:/Users/lenovo/PycharmProjects/Demo/demo.py", line 13, in <module>
    print(name+"age is"+age)
TypeError: can only concatenate str (not "int") to str

　　2.模块

import math
from math import pi,cos,pow 
from math import * 
import math as tmath 
import math as tmath from math import pi as p

import math # 导入整个模块，使用该模块下的函数方式为：math.*
print(math.pi)
r = 2
s = math.pi * r * r
print("圆的面积为：",s)
print("==============================")
from math import pi,cos,pow # 导入math模块下pi.cos.pow函数
print(pi)
r = 2
s = pi * r * r
print("圆的面积为：",s)
print(pow(2,5))
print("==============================")
from math import * # 慎用该方式，只有确定自己想要从给定的模块导入所有功能时，才使用
print(pi)
r = 2
s = pi * r * r
print("圆的面积为：",s)
print("==============================")
import math as tmath # 导入模块并给模块起别名
print(tmath.pi)
r = 2
s = tmath.pi * r * r
print("圆的面积为：",s)
print("==============================")
from math import pi as p # 导入模块下的函数，并给函数起别名
print(p)
r = 2
s = p * r * r
print("圆的面积为：",s)


结果：

3.141592653589793
圆的面积为： 12.566370614359172
==============================
3.141592653589793
圆的面积为： 12.566370614359172
32.0
==============================
3.141592653589793
圆的面积为： 12.566370614359172
==============================
3.141592653589793
圆的面积为： 12.566370614359172
==============================
3.141592653589793
圆的面积为： 12.566370614359172

　　3.赋值魔法

x = 1
print(x)
print("====同时给多个变量赋值====")
x,y,z = 2,3,1
print(x)
print(y)
print(z)
print("====同时给多个变量赋予同样的值====")
a=b=c=2
print(a)
print(b)
print(c)
print("====给某个变量赋予多个值====")
values=1,2,3
print(values)

结果：

1
====同时给多个变量赋值====
2
3
1
====同时给多个变量赋予同样的值====
2
2
2
====给某个变量赋予多个值====
(1, 2, 3)

　　4.增量赋值

# 增量赋值
num = 2
print(num)
print("=============")
# num = num + 1
num += 1
print(num)
print("=============")
num *=2
print(num)
print("=============")
info = "hello"
info +=" world"
print(info)
info *=2
print(info)

 结果：
2
=============
3
=============
6
=============
hello world
hello worldhello world