Section python
1. Integer and Boolean values
1.1 hex conversion
Binary Decimal ----
Binary Decimal ----
The method of calculating ordinary 8421
Decimal Binary turn python Example: bin(51)>>>0b110011
Example Binary Decimal in python: int(0b110011)>>>51
1.2 Boolean value
Only numbers 0 is False, the rest are True
String as long as the content is True, no content is False
Examples
print(bool(""))
print(int(True))
print(int(False))
2. Detailed strings
Strings are ordered, immutable
2.1 Index (accurately and quickly find values)
s = "zhan"
print(s[0])
print(s[-1])
2.2 slice (cut without cutting head trailing)
Gets an interval
s = "zhan_learn_in_oldboy"
print(s[0:10]) # [起始索引:终止索引]
print(s[-6:]) # [起始索引:默认获取字符串末尾的内容]
print(s[11:20])
print(s[:]) # [默认获取字符串开始的内容:默认获取字符串末尾的内容]
对比:
s = "alex_baoyuan|oldboy"
索引
print(s[20]) #报错: string index out of range
切片
print(s[1:100]) # 切片超出索引值不会报错Steps
Step can decide to find direction
It is a positive step from left to right to find
Step right to left to find negative
s = "zhan_learn_in _oldboy"
print(s[0:3]) #步长默认为1
print(s[0:3:2]) #步长为2
Palindrome: Shanghai water from the sea
Example:
user_input = input("请输入你认为的回文：")
if user_input == user_input[::-1]:
print("你输入的是回文")
else:
print("你输入的不是回文")
3. The method of string
s="zhan_learn "
print(s.strip())
print(s.split("_"))
print(s.replace("_","-"))
print(s.upper())
print(s.lower())
print(s.startswith("zh"))
print(s.endswith("sg"))
print(s.count("n"))
# is系列
s = "123你好啊aaaa"
print(s.isalpha()) # 判断是不是由字母,中文组成 -- 返回的是布尔值 ***
print(s.isdigit()) # 判断是否是数字 -- bug
print(s.isdecimal()) # 判断是否是十进制的数 ****
print(s.isalnum()) # 判断是不是字母,数字,汉字
4.for cycle
basic structure
for i in 可迭代对象：
循环体Example:
s = "zhan"
for i in s:
print(i)
Interview questions
问：打印输出的结果
s = '123'
for i in s:
pass
print(i)
问：打印输出的结果
s = "12"
for i in s:
print(s)