Python初学第一天
基础语句
改变变量的特性
weight = int(input('What is your weight(in pounds)? '))
kg_weight = weight * 0.49
print(str(kg_weight) + ‘kg’)
切换使用’ '和" “以及”"" “”"(换行展示)
course = ‘Python for “beginners”’
course = “Pyhon’s course for beginners”
course = ‘’‘Pyhon’s course for “beginners”’’’
[]
course = ‘Python for Beginners’
course[0] # returns the first character
course[1] # returns the second character
course[-1] # returns the first character from the end
course[-2] # returns the second character from the end
course[2:4]#返回第三个至第四个以前的所有字符
course[1:-1]#返回第二个及倒数第二个之前的
course[:]#默认第一个是0，后面是最后
f #format 格式化
first_name = “John”
last_name = “Smith”
msg = f’{first_name} [{last_name}] is a coder’
print(msg)
John [Smith] is a coder
len #计算字符长度
message.upper() # to convert to uppercase
message.lower() # to convert to lowercase
message.title() # to capitalize the first letter of every word
message.find(‘p’) # returns the index of the first occurrence of p （p可以是单词）
(or -1 if not found没有找到)
message.replace(‘p’, ‘q’)替换，注意大小写
‘Python’ in course #布尔函数：寻找Python这个词是否在course字符串中，返回布尔值
计算
/ # returns a float
// # returns an int
% # returns the remainder of division,余数
** # x ^ y
x = x + 10
x += 10扫描二维码关注公众号，回复： 11063713 查看本文章
round #四舍五入取整函数
abs#绝对值
import math #导入函数math
math.函数(变量)
python 3 math module #搜索这个，可以看到函数的意义
IF 判断：
Elif 判断：
else：
is_hot = False
is_cold = True
if is_hot:
print(‘It is a hot day’)
print(‘Drink plenty of water’)
elif is_cold: #shift + tab 结束命令行
print(‘It is a cold day’)
print(‘Wear warm clothes’)
else:
print(‘It is a lovely day’)
逻辑语句
and
or
and not #后一个条件是false
比较
“>”
“==”
“<”
!=
print 举例
weight = int(input(“Please input your weight? “))
unit = input(”(L)bs or (K)g: “)
if unit.upper() == “L”:
print(f"Your weight is {weight*0.45} kg”)
else:
print(f"Your weight is{weight/0.45} pounds”)print 自带回车换行
while语句
i = 1
while i <= 5:
i +=1
print(i)
print(“Done”)
重新命名变量 Shift + F6
