1. Operator
arithmetic operator
| + | add - add two objects | a + b output result 31 |
| - | Subtract - get a negative number or subtract one number from another | a - b output result -11 |
| * | multiply - multiply two numbers or return a string repeated several times | a * b output result 210 |
| / | Divide - x divided by y | b / a output result 2.1 |
| % | Modulo - returns the remainder of the division | b % a output result 1 |
| ** | power - returns x raised to the power of y | a**b is 10 to the 21st power |
| // | Round and divide - Round to the smallest | >>> 9//2 4 |
comparison operator
| == | equals - compares objects for equality |
| != | not equal - compares if two objects are not equal |
| > | greater than - returns whether x is greater than y |
| < | less than - Returns whether x is less than y. All comparison operators return 1 for true and 0 for false. These are equivalent to the special variables True and False, respectively. Note the capitalization of these variable names. |
| >= | greater than or equal to - Returns whether x is greater than or equal to y. |
| <= | Less than or equal to - Returns whether x is less than or equal to y. |
assignment operator
| = | simple assignment operator | c = a + b assign the operation result of a + b to c |
| += | Additive assignment operator | c += a is equivalent to c = c + a |
| -= | subtraction assignment operator | c -= a is equivalent to c = c - a |
| *= | multiplication assignment operator | c *= a is equivalent to c = c * a |
| /= | division assignment operator | c /= a is equivalent to c = c / a |
| %= | modulo assignment operator | c %= a is equivalent to c = c % a |
| **= | power assignment operator | c **= a is equivalent to c = c ** a |
| //= | integer division assignment operator | c //= a is equivalent to c = c // a |
bitwise operator
| & | Bitwise AND: 1 if both are 1, otherwise 0 |
| | | Bitwise OR: 1 if there is only one 1 |
| ~ | Inversion: when 0 is 1, when 1 is 0 |
| ^ | Bitwise XOR: 1 and 0 are 1, otherwise 0 |
| << | Left shift: how much you shift to the left, you will delete the previous number, and then add the corresponding number at the end |
| >> | Move right: How much is moved to the right, how much will be deleted at the end, and then the head will be added accordingly |
Logical Operators
| and | 1 and 1 == 1 |
| or | 1 or 0 == 1 |
| not | not 1 ==0 |
member operator
| in | x exists in the specified sequence, then it is 1 |
| not in |
identity operator
| is | is is to judge whether two identifiers refer to an object | x is y , like id(x) == id(y) , returns True if they refer to the same object, otherwise returns False |
| is not | is not is to judge whether two identifiers refer to different objects | x is not y , like id(x) != id(y) . Returns True if the reference is not the same object, False otherwise. |
number
int integer
floatfloat type
complex plural:
a + bj,或者complex(a,b)convert
int(var) : Convert var to an integer
float(var) : convert var to float
complex(var) or complex(x, y): convert var to complex
num1 = "12"
num2 = int(num1)
num3 = "1.23"
num4 = float(num3) Common Mathematical Functions
| abs(x) | take the absolute value |
| sqrt(x) | prescription |
| pow(x, y) | x**y |
constant
| pi | The mathematical constant pi (pi, generally expressed in π) |
| e | The mathematical constant e, e is the natural constant (natural constant). |
2. string
Via ' or ' ' . Generally, you can get the value of the corresponding element with [] . (Starting from 0, -1 takes the last element)
(Quoted from rookie tutorial python)
escape character
\n : Newline
\t ：tab
\" ："
\' ：'
format character (similar to c language)
Emphasis on the str.format() function
Python format formatting function | rookie tutorial (runoob.com)
f-string
triple quotes
三引号允许字符串跨多行字符串中可以包含换行符、制表符以及其他特殊字符
常见的字符串相关函数
3.列表
列表类似于数组，下表从0开始索引，可以从-1（末尾）开始往前遍历
同时，可以通过list[num]获取对应下标的值
常见的与列表相关的函数
len(list) == 得到列表的长度
max(list) == 得到列表最大元素
min(list) == 得到列表最小元素
方法：
list.append(num) == 末尾添加新元素
list.count(num) == 统计num在列表中出现的次数
list.extend(seq) == 在末尾追加另一个列表
list.index(obj) == 找到obj的下标
list.insert(index, obj) == 插入
list.pop([index = -1]) == 弹出一个元素，默认为最后一个
list.remove(obj) == 移除obj，没有返回值，只删除第一个obj
list.reverse() == 反转
list.sort() == 排序
list.clear() == 清空
list.copy() == 复制
4.元组
元组与列表类似，但是元组中的元素不能修改，但可通过del 删除真个元组
元组使用 () ， 而列表使用 []
下标索引从 0 开始，可以进行截取
5.字典
6.集合